/* ?? Physics Lab: professional full-bleed bench layout ?? */

.physics-shell {
  width: 100%;
  box-sizing: border-box;
  padding: 0.75rem 1rem 1.5rem;
}

.physics-shell--lab {
  padding: 0.4rem 0.75rem 0.5rem;
  display: flex;
  flex-direction: column;
  height: calc(100dvh - 64px);
  min-height: 0;
  box-sizing: border-box;
}

.physics-shell--seo {
  padding-top: 1.25rem;
  padding-bottom: 2.5rem;
  background: #fff;
}

@media (min-width: 1024px) {
  .physics-shell {
    padding: 0.85rem 1.25rem 1.75rem;
  }

  .physics-shell--lab {
    padding: 0.4rem 1rem 0.55rem;
    height: calc(100dvh - 72px);
  }
}

.physics-page {
  background: var(--color-surface-soft, #f4f6f9);
  min-height: calc(100dvh - 72px);
}

.physics-page--lab {
  min-height: 0;
}

body.physics-focus-on .physics-shell--lab {
  height: 100dvh;
  padding: 0.45rem 0.65rem;
}

.physics-sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* SEO under lab ? TOC (left) + reading column (right) */
.physics-exp-seo {
  margin: 0 auto;
  padding: 1.25rem 1.25rem 1.75rem;
  width: 100%;
  max-width: 72rem;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1.5rem 2rem;
  align-items: start;
  box-sizing: border-box;
  background: #fff;
}

@media (min-width: 960px) {
  .physics-exp-seo {
    grid-template-columns: 14.5rem minmax(0, 42rem);
    justify-content: center;
    padding-left: 1.5rem;
    padding-right: 1.5rem;
  }
}

.physics-exp-seo__toc {
  margin: 0;
  padding: 0.85rem 0.9rem;
  border: 1px solid #e8edf3;
  border-radius: 12px;
  background: #fafbfc;
}

@media (min-width: 960px) {
  .physics-exp-seo__toc {
    position: sticky;
    /* Clear sticky .landing-header (64px / 72px) */
    top: calc(64px + 0.75rem);
    max-height: calc(100dvh - 64px - 1.5rem);
    overflow: auto;
  }
}

@media (min-width: 1024px) {
  .physics-exp-seo__toc {
    top: calc(72px + 0.75rem);
    max-height: calc(100dvh - 72px - 1.5rem);
  }
}

.physics-exp-seo__toc-title {
  margin: 0 0 0.55rem;
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #64748b;
}

.physics-exp-seo__toc-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
}

@media (max-width: 959px) {
  .physics-exp-seo__toc-list {
    flex-direction: row;
    flex-wrap: wrap;
    gap: 0.3rem 0.45rem;
  }
}

.physics-exp-seo__toc-list a {
  display: block;
  padding: 0.28rem 0.35rem;
  border-radius: 6px;
  font-size: 0.82rem;
  font-weight: 600;
  line-height: 1.35;
  color: #475569;
  text-decoration: none;
}

.physics-exp-seo__toc-list a:hover {
  color: var(--color-brand, #2260e8);
  background: #fff;
}

@media (max-width: 959px) {
  .physics-exp-seo__toc-list a {
    padding: 0.22rem 0.5rem;
    border: 1px solid #e2e8f0;
    background: #fff;
    font-size: 0.78rem;
  }
}

.physics-exp-seo__main {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
}

.physics-exp-seo__lead-title,
.physics-exp-seo__guide-sec,
.physics-exp-seo__faq-title,
.physics-exp-seo__study-title {
  scroll-margin-top: calc(64px + 1rem);
}

@media (min-width: 1024px) {
  .physics-exp-seo__lead-title,
  .physics-exp-seo__guide-sec,
  .physics-exp-seo__faq-title,
  .physics-exp-seo__study-title {
    scroll-margin-top: calc(72px + 1rem);
  }
}

.physics-exp-seo__eyebrow {
  margin: 0 0 0.35rem;
  font-size: 0.72rem;
  font-weight: 750;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #b45309;
}

.physics-exp-seo__mini-label {
  margin: 0 0 0.45rem;
  font-size: 0.78rem;
  font-weight: 750;
  color: #64748b;
}

.physics-exp-seo__prose {
  margin: 0;
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--color-body, #334155);
}

.physics-exp-seo__note {
  margin: 0.55rem 0 0;
  font-size: 0.86rem;
  line-height: 1.55;
  color: var(--color-muted, #64748b);
}

/* Layer 0 ? light context strip */
.physics-exp-seo__context {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  margin: 0;
  padding: 0 0 0.15rem;
  border-bottom: 1px solid #e8edf3;
}

.physics-exp-seo__context-module {
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.5;
  color: #64748b;
}

.physics-exp-seo__context-module a {
  font-weight: 700;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-exp-seo__context-module a:hover {
  text-decoration: underline;
}

.physics-exp-seo__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0;
  padding: 0 0 0.85rem;
  list-style: none;
}

.physics-exp-seo__tags li {
  margin: 0;
  padding: 0;
  border-radius: 999px;
  font-size: 0.74rem;
  font-weight: 650;
  color: #475569;
  background: #f1f5f9;
  border: 1px solid #e2e8f0;
}

.physics-exp-seo__tags a {
  display: inline-block;
  padding: 0.22rem 0.55rem;
  color: inherit;
  text-decoration: none;
}

.physics-exp-seo__tags a:hover {
  color: var(--color-brand, #2260e8);
}

/* Layer 1 ? single entry card */
.physics-exp-seo__lead {
  margin: 0;
  padding: 1.25rem 1.3rem 1.35rem;
  border-radius: 16px;
  border: 1px solid color-mix(in oklab, #f59e0b 28%, #e2e8f0);
  background:
    linear-gradient(180deg, #fffbeb 0%, #fff 42%),
    #fff;
  box-shadow: 0 1px 2px rgb(15 23 42 / 4%);
}

.physics-exp-seo__lead-title {
  margin: 0 0 0.65rem;
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.25;
  color: var(--color-ink, #0f172a);
}

.physics-exp-seo__lead-cue {
  margin: 0.7rem 0 0;
  padding: 0.55rem 0.7rem;
  border-radius: 8px;
  border-left: 3px solid #f59e0b;
  background: rgb(255 251 235 / 0.85);
  font-size: 0.88rem;
  font-weight: 600;
  line-height: 1.55;
  color: #92400e;
}

.physics-exp-seo__lead-formulas,
.physics-exp-seo__lead-how {
  margin-top: 1.1rem;
  padding-top: 0.95rem;
  border-top: 1px solid #f1e7d0;
}

.physics-exp-seo__formulas {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.physics-exp-seo__formulas--inline {
  gap: 0.4rem;
}

@media (min-width: 640px) {
  .physics-exp-seo__formulas--inline {
    flex-direction: row;
    flex-wrap: wrap;
  }

  .physics-exp-seo__formulas--inline li {
    flex: 1 1 12rem;
  }
}

.physics-exp-seo__formulas code {
  display: block;
  padding: 0.5rem 0.65rem;
  border-radius: 8px;
  border: 1px solid #e7e0d2;
  background: #fff;
  font-size: 0.9rem;
  font-weight: 700;
  line-height: 1.4;
  color: var(--color-ink, #0f172a);
  font-variant-numeric: tabular-nums;
}

.physics-exp-seo__steps {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
}

.physics-exp-seo__steps li {
  display: flex;
  gap: 0.65rem;
  align-items: flex-start;
  margin: 0;
  padding: 0;
  background: transparent;
  border: 0;
}

.physics-exp-seo__step-num {
  flex: 0 0 auto;
  width: 1.45rem;
  height: 1.45rem;
  margin-top: 0.1rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 800;
  color: #fff;
  background: #b45309;
}

.physics-exp-seo__step-text {
  flex: 1;
  min-width: 0;
  font-size: 0.9rem;
  line-height: 1.55;
  color: var(--color-body, #334155);
}

/* Layer 2 ? continuous study document */
.physics-exp-seo__study {
  margin: 0;
  padding: 0;
}

.physics-exp-seo__study-head {
  margin: 0 0 1rem;
  padding-bottom: 0.85rem;
  border-bottom: 2px solid #0f172a;
}

.physics-exp-seo__study-title {
  margin: 0 0 0.55rem;
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: -0.015em;
  color: var(--color-ink, #0f172a);
}

.physics-exp-seo__guide-sections {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* —— Mind map host (rendered by markmap-view) —— */
.physics-mindmap {
  margin: 0 0 1.5rem;
  padding: 0;
}

.physics-mindmap__caption {
  margin: 0 0 0.75rem;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-muted, #64748b);
}

.physics-mindmap__markmap {
  margin: 0;
}

.physics-mindmap__host {
  height: min(52vh, 440px);
  min-height: 280px;
  border-radius: 14px;
  overflow: hidden;
  background:
    radial-gradient(90% 70% at 12% 20%, #eef4ff 0%, transparent 55%),
    linear-gradient(180deg, #f8fafc 0%, #ffffff 100%);
  border: 1px solid #e2e8f0;
}

.physics-mindmap__host svg {
  display: block;
  width: 100%;
  height: 100%;
}

.physics-mindmap__hint {
  margin: 0.45rem 0 0;
  font-size: 0.75rem;
  line-height: 1.4;
  color: #64748b;
}

.physics-mindmap--compact {
  margin: 0.75rem 0 1.1rem;
}

.physics-mindmap--compact .physics-mindmap__host {
  height: min(40vh, 320px);
  min-height: 220px;
}

/* Keep a light canvas inside dark guide modals — markmap text assumes light bg. */
.physics-spring-guide .physics-mindmap__host,
.physics-reflect-guide .physics-mindmap__host {
  background:
    radial-gradient(90% 70% at 12% 20%, #e8eef8 0%, transparent 55%),
    linear-gradient(180deg, #f1f5f9 0%, #ffffff 100%);
  border-color: #334155;
}

.physics-spring-guide .physics-mindmap__hint,
.physics-reflect-guide .physics-mindmap__hint {
  color: #94a3b8;
}

/* Ensure markmap node labels stay high-contrast on the light canvas. */
.physics-mindmap__host .markmap-foreign {
  color: #0f172a;
}

.physics-mindmap__host .markmap-foreign div {
  color: inherit;
}

.physics-exp-seo__guide-sec {
  margin: 0;
  padding: 1rem 0 1.05rem;
  border-bottom: 1px solid #e8edf3;
  background: transparent;
  box-shadow: none;
  border-radius: 0;
}

.physics-exp-seo__guide-sec:last-child {
  border-bottom: 0;
  padding-bottom: 0.25rem;
}

.physics-exp-seo__subheading {
  margin: 0 0 0.45rem;
  padding: 0;
  border: 0;
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.35;
  color: var(--color-ink, #0f172a);
}

.physics-exp-seo__guide-sec .physics-exp-seo__prose + .physics-exp-seo__prose {
  margin-top: 0.5rem;
}

.physics-exp-seo__bullets,
.physics-exp-seo__guide-steps {
  margin: 0.4rem 0 0;
  padding-left: 1.2rem;
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--color-body, #334155);
}

.physics-exp-seo__bullets li + li,
.physics-exp-seo__guide-steps li + li {
  margin-top: 0.35rem;
}

.physics-exp-seo__guide-formulas {
  margin: 0.6rem 0 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.physics-exp-seo__guide-formulas li {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 0.55rem 0.65rem;
  border-radius: 8px;
  background: #f8fafc;
  border: 1px solid #e8edf3;
}

.physics-exp-seo__guide-formulas code {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
}

.physics-exp-seo__guide-formulas span {
  font-size: 0.84rem;
  line-height: 1.5;
  color: var(--color-muted, #64748b);
}

.physics-exp-seo__formula-details {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px dashed #cbd5e1;
}

.physics-exp-seo__formula-grid {
  display: grid;
  gap: 0.5rem;
}

@media (min-width: 640px) {
  .physics-exp-seo__formula-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.physics-exp-seo__formula-card {
  margin: 0;
  padding: 0.6rem 0.7rem;
  border-radius: 8px;
  border: 1px solid #e2e8f0;
  background: #f8fafc;
}

.physics-exp-seo__formula-card-title {
  display: block;
  margin-bottom: 0.25rem;
  font-size: 0.74rem;
  font-weight: 700;
  color: #64748b;
}

.physics-exp-seo__formula-card code {
  display: block;
  font-size: 0.88rem;
  font-weight: 700;
  line-height: 1.45;
  color: var(--color-ink, #0f172a);
  font-variant-numeric: tabular-nums;
}

/* Layer 3 ? FAQ quieter */
.physics-exp-seo__faq-block {
  margin: 0;
  padding: 0;
}

.physics-exp-seo__faq-title {
  margin: 0 0 0.65rem;
  font-size: 1rem;
  font-weight: 800;
  color: #475569;
}

.physics-exp-seo__faq {
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0;
  border-top: 1px solid #e2e8f0;
}

.physics-exp-seo__faq-item {
  margin: 0;
  padding: 0.75rem 0;
  border-bottom: 1px solid #eef2f7;
  background: transparent;
  border-radius: 0;
}

.physics-exp-seo__faq-item dt {
  margin: 0;
  font-size: 0.9rem;
  font-weight: 750;
  color: var(--color-ink, #0f172a);
}

.physics-exp-seo__faq-item dd {
  margin: 0.3rem 0 0;
  font-size: 0.88rem;
  line-height: 1.55;
  color: var(--color-body, #475569);
}

.physics-exp-seo__more {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0.75rem;
  margin: 0;
  padding-top: 0.25rem;
}

.physics-exp-seo__siblings {
  flex: 1 1 100%;
  margin: 0 0 0.35rem;
}

.physics-exp-seo__sibling-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.85rem;
  margin: 0.35rem 0 0;
  padding: 0;
  list-style: none;
}

.physics-exp-seo__sibling-list a {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-exp-seo__sibling-list a:hover {
  text-decoration: underline;
}

.physics-exp-seo__more-link {
  display: inline-flex;
  align-items: center;
  padding: 0.4rem 0.75rem;
  border-radius: 8px;
  border: 1px solid #e2e8f0;
  background: #fff;
  font-size: 0.84rem;
  font-weight: 650;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-exp-seo__more-link:hover {
  background: #f8fafc;
}

.physics-page--lab .physics-workspace {
  flex: 1 1 auto;
  min-height: 0;
  margin-bottom: 0;
  display: flex;
  flex-direction: column;
}

.physics-embed--fill {
  flex: 1 1 auto;
  min-height: 0;
  height: 100%;
  display: flex;
  flex-direction: column;
}

.physics-embed--fill > * {
  flex: 1 1 auto;
  min-height: 0;
  height: 100%;
}

.physics-labbar {
  flex: 0 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.45rem 0.85rem;
  margin-bottom: 0.4rem;
  min-height: 1.75rem;
}

.physics-labbar__crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.3rem;
  font-size: 0.78rem;
  color: var(--color-muted, #64748b);
  min-width: 0;
  flex: 1 1 auto;
}

.physics-labbar__crumbs a {
  color: inherit;
  text-decoration: none;
}

.physics-labbar__crumbs a:hover {
  color: var(--color-brand);
  text-decoration: underline;
}

.physics-labbar__title {
  margin: 0;
  display: inline;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.05rem, 1.6vw, 1.25rem);
  font-weight: 650;
  letter-spacing: -0.02em;
  color: var(--color-ink, #0f172a);
  line-height: 1.25;
}

.physics-labbar__mvp {
  display: inline-flex;
  align-items: center;
  margin-left: 0.35rem;
  padding: 0.18rem 0.55rem;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #92400e;
  background: linear-gradient(
    135deg,
    color-mix(in oklab, #fbbf24 55%, #fff),
    color-mix(in oklab, #f59e0b 28%, #fff)
  );
  border: 1px solid color-mix(in oklab, #d97706 35%, #fde68a);
  vertical-align: middle;
}

.physics-labbar__mvp-note {
  margin: 0;
  flex: 1 1 100%;
  font-size: 0.78rem;
  color: #92400e;
  line-height: 1.4;
  padding: 0.35rem 0.55rem;
  border-radius: 0.55rem;
  background: color-mix(in oklab, #fbbf24 14%, #fff);
  border: 1px solid color-mix(in oklab, #f59e0b 22%, #fde68a);
}

.physics-hub__exp-badge--mvp {
  background: linear-gradient(
    135deg,
    color-mix(in oklab, #fbbf24 50%, #fff),
    color-mix(in oklab, #f59e0b 22%, #fff)
  );
  color: #92400e;
  border: 1px solid color-mix(in oklab, #d97706 30%, #fde68a);
  font-weight: 800;
  letter-spacing: 0.05em;
}

.physics-hub__module-mvp {
  display: inline-flex;
  align-items: center;
  padding: 0.12rem 0.45rem;
  border-radius: 999px;
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: #92400e;
  background: color-mix(in oklab, #fbbf24 22%, #fff);
  border: 1px solid color-mix(in oklab, #f59e0b 28%, #fde68a);
}

.physics-mvp-banner {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  margin: 0 0 0.85rem;
  padding: 0.55rem 0.65rem;
  border-radius: 0.7rem;
  background: color-mix(in oklab, #fbbf24 16%, #fff);
  border: 1px solid color-mix(in oklab, #f59e0b 30%, #fde68a);
}

.physics-mvp-banner__badge {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  padding: 0.15rem 0.45rem;
  border-radius: 999px;
  font-size: 0.68rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: #fff;
  background: #d97706;
}

.physics-mvp-banner__text {
  font-size: 0.78rem;
  line-height: 1.4;
  color: #92400e;
  font-weight: 600;
}

.physics-mvp-chip {
  display: inline-flex;
  align-items: center;
  margin-right: 0.4rem;
  padding: 0.08rem 0.4rem;
  border-radius: 999px;
  font-size: 0.62rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  vertical-align: middle;
  color: #92400e;
  background: color-mix(in oklab, #fbbf24 35%, #fff);
  border: 1px solid color-mix(in oklab, #d97706 28%, #fde68a);
}

.physics-side-note--mvp {
  margin-top: 0.35rem;
  padding: 0.45rem 0.55rem;
  border-radius: 0.55rem;
  color: #92400e;
  background: color-mix(in oklab, #fbbf24 12%, #fff);
  border: 1px solid color-mix(in oklab, #f59e0b 22%, transparent);
  font-weight: 600;
}

/* Legacy topbar (hub / module pages) */
.physics-topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem 1.25rem;
  margin-bottom: 0.85rem;
}

.physics-topbar-main {
  min-width: 0;
  flex: 1 1 18rem;
}

.physics-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  color: var(--color-muted, #64748b);
  margin-bottom: 0.35rem;
}

.physics-crumbs a {
  color: inherit;
  text-decoration: none;
}

.physics-crumbs a:hover {
  color: var(--color-brand);
  text-decoration: underline;
}

.physics-crumbs-sep {
  opacity: 0.55;
}

.physics-topbar-title-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.55rem 0.75rem;
}

.physics-title {
  margin: 0;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.35rem, 2.2vw, 1.75rem);
  font-weight: 650;
  letter-spacing: -0.02em;
  color: var(--color-ink, #0f172a);
  line-height: 1.2;
}

.physics-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.physics-tags li {
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 650;
  color: var(--color-brand);
  background: var(--color-brand-tint, #e8f0fe);
}

.physics-lead {
  margin: 0.35rem 0 0;
  max-width: 52rem;
  font-size: 0.9rem;
  line-height: 1.45;
  color: var(--color-muted, #64748b);
}

.physics-lead--compact {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.physics-topbar-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.45rem;
  flex-shrink: 0;
  padding-top: 0.15rem;
}

.physics-topbar-actions .btn-secondary {
  font-size: 0.8rem;
  padding: 0.35rem 0.7rem;
  text-decoration: none;
}

.physics-workspace {
  width: 100%;
}

.physics-embed {
  width: 100%;
}

.physics-about {
  margin-top: 1rem;
  padding-top: 0.85rem;
  border-top: 1px solid var(--color-hairline, #e2e8f0);
}

.physics-about h2 {
  margin: 0 0 0.35rem;
  font-size: 0.95rem;
  font-weight: 650;
  color: var(--color-ink, #0f172a);
}

.physics-about p {
  margin: 0;
  font-size: 0.88rem;
  line-height: 1.55;
  color: var(--color-body, #475569);
  max-width: 60rem;
}

/* ?? Experiment bench: controls | stage | side ?? */

.physics-bench {
  display: grid;
  grid-template-columns: minmax(15rem, 17.5rem) minmax(0, 1fr) minmax(14rem, 16.5rem);
  grid-template-rows: minmax(0, 1fr) auto;
  min-height: calc(100dvh - 11.5rem);
  width: 100%;
  border: 1px solid var(--color-hairline, #d8dee8);
  border-radius: 14px;
  overflow: hidden;
  background: #fff;
  box-shadow: 0 1px 2px rgb(15 23 42 / 4%), 0 8px 24px rgb(15 23 42 / 4%);
}

.physics-bench--no-chart {
  grid-template-rows: minmax(0, 1fr);
}

/* Two-column lab: left rail (params + readouts) | right (stage + chart) */
.physics-bench--split2 {
  grid-template-columns: minmax(18rem, 20.5rem) minmax(0, 1fr);
  grid-template-rows: minmax(0, 1fr);
  height: 100%;
  min-height: 0;
}

.physics-bench--split2 .physics-bench__controls {
  grid-column: 1;
  grid-row: 1;
  gap: 0;
  padding: 0;
  background: #f7f8fb;
}

.physics-bench--split2 .physics-bench__block {
  padding: 0.9rem 1rem;
}

.physics-bench--split2 .physics-bench__block + .physics-bench__block,
.physics-bench--split2 .physics-spring-demo {
  border-top: 1px solid var(--color-hairline, #e2e8f0);
}

.physics-bench--split2 .physics-bench__block--readouts {
  background: #eef3fb;
}

.physics-bench--split2 .physics-bench__block--formulas {
  margin-top: auto;
  background: #fff;
}

.physics-bench--split2 .physics-spring-demo {
  margin: 0;
  border-radius: 0;
  border-left: 0;
  border-right: 0;
  border-bottom: 0;
  padding: 0.85rem 1rem;
}

.physics-bench--split2 .physics-bench__main {
  grid-column: 2;
  grid-row: 1;
  display: grid;
  grid-template-rows: minmax(0, 1.35fr) minmax(12rem, 0.85fr);
  min-width: 0;
  min-height: 0;
  background: #0f1419;
}

.physics-bench--split2 .physics-bench__stage {
  grid-column: auto;
  grid-row: auto;
  min-height: 0;
}

.physics-bench--split2 .physics-bench__chart {
  grid-column: auto;
  grid-row: auto;
  padding: 0.55rem 0.75rem 0.7rem;
}

/* Spring lab: toolbar + sidebar | main(stage/chart) */
.physics-bench--spring {
  display: grid;
  grid-template-columns: minmax(17.5rem, 20rem) minmax(0, 1fr);
  grid-template-rows: auto minmax(0, 1fr);
  height: 100%;
  min-height: 0;
  width: 100%;
  position: relative;
  border: 1px solid var(--color-hairline, #d8dee8);
  border-radius: 14px;
  overflow: hidden;
  background: #fff;
  box-shadow: 0 1px 2px rgb(15 23 42 / 4%), 0 8px 24px rgb(15 23 42 / 4%);
  /* Shared demo outer-glow ? soft sunlight, not saturated amber */
  --demo-glow-room: 0.55rem;
  --demo-glow-radius: 12px;
  --demo-glow-color: #e8c96a;
  --demo-glow-border: 2.5px solid color-mix(in oklab, var(--demo-glow-color) 78%, #fff);
  --demo-glow-ring: 0 0 0 3px color-mix(in oklab, var(--demo-glow-color) 28%, transparent);
  --demo-glow-soft: 0 0 12px 4px color-mix(in oklab, var(--demo-glow-color) 38%, transparent);
  --demo-glow-bloom: 0 0 18px 6px color-mix(in oklab, var(--demo-glow-color) 20%, transparent);
  --demo-glow-ring-mid: 0 0 0 4px color-mix(in oklab, var(--demo-glow-color) 36%, transparent);
  --demo-glow-soft-mid: 0 0 15px 5px color-mix(in oklab, var(--demo-glow-color) 46%, transparent);
  --demo-glow-bloom-mid: 0 0 22px 8px color-mix(in oklab, var(--demo-glow-color) 26%, transparent);
}

.physics-bench--spring:fullscreen,
.physics-bench--spring.physics-bench--focus {
  border-radius: 0;
  border: 0;
}

.physics-bench--spring .physics-bench__toolbar {
  grid-column: 1 / -1;
  grid-row: 1;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.45rem 0.75rem;
  padding: 0.4rem 0.75rem;
  border-bottom: 1px solid var(--color-hairline, #e2e8f0);
  background: #f8fafc;
}

.physics-bench--spring .physics-bench__lead {
  margin: 0;
  max-width: min(52rem, 100%);
  min-width: 0;
  font-size: 0.8rem;
  line-height: 1.45;
  font-weight: 550;
  color: var(--color-body, #475569);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.physics-bench--spring .physics-bench__lead strong {
  font-weight: 750;
  color: var(--color-ink, #0f172a);
}

.physics-bench--spring .physics-bench__lead em {
  font-style: normal;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--color-brand, #2260e8);
}

.physics-bench--spring .physics-bench__lead-t {
  white-space: nowrap;
}

@media (max-width: 900px) {
  .physics-bench--spring .physics-bench__lead {
    white-space: normal;
  }
}

.physics-bench--spring .physics-bench__tools {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.physics-bench--spring .physics-bench__tools .btn-secondary,
.physics-bench--spring .physics-bench__tools .btn-brand {
  font-size: 0.78rem;
  padding: 0.3rem 0.6rem;
}

.physics-bench--spring .physics-spring-demo-card {
  position: absolute;
  z-index: 30;
  left: 50%;
  bottom: 0.75rem;
  --drag-x: 0px;
  --drag-y: 0px;
  transform: translate(calc(-50% + var(--drag-x)), var(--drag-y));
  width: min(26rem, calc(100% - 1.5rem));
  max-height: min(40%, 16rem);
  overflow: auto;
  padding: 0.7rem 0.8rem 0.65rem;
  border-radius: 12px;
  border: 1px solid var(--color-hairline, #e2e8f0);
  background: rgb(255 255 255 / 97%);
  box-shadow: 0 10px 28px rgb(15 23 42 / 16%);
  backdrop-filter: blur(8px);
  touch-action: none;
}

.physics-bench--spring .physics-spring-demo-card__title {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.5rem;
  margin: 0 0 0.45rem;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
  cursor: grab;
}

.physics-bench--spring .physics-spring-demo-card__title h3 {
  margin: 0.1rem 0 0;
  font-size: 0.95rem;
  font-weight: 750;
  line-height: 1.3;
  color: var(--color-ink, #0f172a);
}

.physics-bench--spring .physics-spring-demo-card__body {
  margin: 0 0 0.65rem;
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--color-body, #475569);
}

.physics-bench--spring .physics-spring-demo-card__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  justify-content: flex-end;
}

.physics-bench--spring .physics-spring-demo-card__actions .btn-secondary:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

/* Unified left column: params scroll + playback + readouts */
.physics-bench--spring .physics-bench__sidebar {
  grid-column: 1;
  grid-row: 2;
  display: flex;
  flex-direction: column;
  min-height: 0;
  min-width: 0;
  overflow: hidden;
  position: relative;
  border-right: 1px solid var(--color-hairline, #e2e8f0);
  background: #f7f8fa;
}

.physics-bench--spring .physics-section-title--panel {
  margin: 0 0 0.55rem;
  padding-bottom: 0.35rem;
  border-bottom: 2px solid color-mix(in oklab, var(--color-brand, #2260e8) 32%, #e2e8f0);
  font-size: 0.92rem;
  font-weight: 800;
  letter-spacing: 0.01em;
  text-transform: none;
  color: var(--color-ink, #0f172a);
}

.physics-bench--spring .physics-section-title--sub {
  margin: 0 0 0.3rem;
  font-size: 0.8rem;
  font-weight: 750;
  letter-spacing: 0.01em;
  text-transform: none;
  color: var(--color-ink, #1e293b);
}

.physics-bench--spring .physics-field__label {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem;
  font-size: 0.84rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
}

.physics-bench--spring .physics-field__label em {
  font-style: normal;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--color-brand, #2260e8);
}

.physics-bench--spring .physics-bench__params-scroll {
  flex: 1 1 0%;
  min-height: 0;
  overflow: auto;
  padding: 0.55rem calc(0.85rem + var(--demo-glow-room) * 0.35) 0.35rem;
  scrollbar-width: thin;
  scrollbar-color: #cbd5e1 transparent;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.physics-bench--spring .physics-param-group {
  margin: 0;
  padding: 0.55rem 0.6rem 0.6rem;
  border: 1px solid var(--color-hairline, #e2e8f0);
  border-radius: 10px;
  background: #fff;
  box-shadow: 0 1px 0 rgb(15 23 42 / 3%);
}

.physics-bench--spring .physics-param-group__title {
  margin: 0 0 0.15rem;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.01em;
  color: var(--color-ink, #0f172a);
}

.physics-bench--spring .physics-param-group__desc {
  margin: 0 0 0.5rem;
  font-size: 0.7rem;
  line-height: 1.35;
  font-weight: 550;
  color: var(--color-muted, #64748b);
}

.physics-bench--spring .physics-bench__params-scroll .physics-field {
  margin-bottom: 0.55rem;
}

.physics-bench--spring .physics-bench__params-scroll .physics-field:last-child {
  margin-bottom: 0;
}

.physics-bench--spring .physics-field--inline {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  margin-bottom: 0.4rem;
}

.physics-bench--spring .physics-field--inline .physics-field__name {
  flex: 0 1 auto;
  min-width: 4.5rem;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
  white-space: nowrap;
}

.physics-bench--spring .physics-field--inline .physics-stepper {
  flex: 1 1 auto;
  min-width: 0;
  max-width: 9.5rem;
  margin-left: auto;
}

.physics-bench--spring .physics-field--inline .physics-field__unit {
  flex: 0 0 auto;
  min-width: 2.1rem;
  font-style: normal;
  font-size: 0.78rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--color-brand, #2260e8);
}

.physics-bench--spring .physics-field-hint {
  margin: 0.2rem 0 0;
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--color-body, #475569);
}

.physics-bench--spring .physics-bench__params-scroll .physics-layer-row {
  margin: 0;
  gap: 0.35rem 0.55rem;
}

.physics-bench--spring .physics-bench__params-scroll .physics-check {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--color-ink, #1e293b);
}

.physics-bench--spring .physics-bench__playback {
  flex: 0 0 auto;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  /* Side inset for demo glow; keep vertical stack tight */
  margin: 0.25rem calc(var(--demo-glow-room) + 6px) 0;
  padding: 0.45rem 0.75rem;
  border: 1px solid var(--color-hairline, #e2e8f0);
  border-radius: var(--demo-glow-radius, 12px);
  background: #eef2f7;
}

.physics-bench--spring .physics-bench__playback .physics-actions--toolbar {
  margin: 0;
  padding: 0;
  border: 0;
}

.physics-bench--spring .physics-bench__playback .physics-side-note {
  margin: 0;
  font-size: 0.7rem;
  line-height: 1.35;
  font-weight: 550;
  color: var(--color-muted, #64748b);
}

.physics-bench--spring .physics-bench__readouts {
  flex: 0 0 auto;
  margin: 0.25rem calc(var(--demo-glow-room) + 6px) calc(var(--demo-glow-room) + 6px);
  padding: 0.45rem 0.75rem 0.55rem;
  border: 1px solid var(--color-hairline, #d8dee8);
  border-radius: var(--demo-glow-radius, 12px);
  background: #fff;
  overflow: visible;
  min-height: 0;
}

.physics-bench--spring .physics-bench__readouts .physics-section-title--panel {
  margin-bottom: 0.4rem;
  font-size: 0.88rem;
}

.physics-bench--spring .physics-readout--spring {
  gap: 0.35rem;
}

.physics-bench--spring .physics-readout--spring > div {
  padding: 0.35rem 0.45rem;
  border: 1px solid color-mix(in oklab, var(--color-brand, #2260e8) 14%, #e2e8f0);
  background: #fff;
  box-shadow: none;
}

.physics-bench--spring .physics-readout--spring dt {
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0;
  color: #64748b;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.physics-bench--spring .physics-readout--spring dd {
  margin-top: 0.08rem;
  font-size: 0.92rem;
  font-weight: 800;
  color: var(--color-ink, #0f172a);
  letter-spacing: -0.01em;
  font-variant-numeric: tabular-nums;
}

.physics-bench--spring .physics-bench__main {
  grid-column: 2;
  grid-row: 2;
  display: grid;
  grid-template-rows: minmax(0, 1fr) minmax(12rem, 32vh);
  gap: 0;
  padding: 0.35rem;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
  position: relative;
  background: #f7f8fa;
}

/*
 * Clip slots: same bg as main (invisible). Padding = glow room.
 * Spotlight stays inside the slot so stage glow never paints the chart.
 */
.physics-bench--spring .physics-bench__stage-slot,
.physics-bench--spring .physics-bench__chart-slot {
  position: relative;
  overflow: hidden;
  min-width: 0;
  min-height: 0;
  background: transparent;
}

.physics-bench--spring .physics-bench__stage-slot {
  grid-column: 1;
  grid-row: 1;
  display: flex;
  flex-direction: column;
  padding: var(--demo-glow-room) var(--demo-glow-room) 0.35rem;
}

.physics-bench--spring .physics-bench__chart-slot {
  grid-column: 1;
  grid-row: 2;
  display: flex;
  flex-direction: column;
  padding: 0.35rem var(--demo-glow-room) var(--demo-glow-room);
}

.physics-bench--spring .physics-bench__stage {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  min-width: 0;
  position: relative;
  overflow: hidden;
  border: 1px solid rgb(71 85 105 / 55%);
  border-radius: 12px;
  background: #0f1419;
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 4%);
}

.physics-bench--spring .physics-bench__stage .physics-stage-2d {
  min-height: 0;
}

.physics-bench--spring .physics-bench__chart {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  min-width: 0;
  padding: 0.45rem 0.55rem 0.5rem;
  border: 1px solid rgb(71 85 105 / 55%);
  border-radius: 12px;
  background: #0f1419;
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 4%);
  overflow: hidden;
  position: relative;
}

.physics-bench--spring .physics-spring-charts {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
}

.physics-bench--spring .physics-spring-charts__canvas {
  flex: 1 1 auto;
  min-height: 0;
  position: relative;
}

.physics-bench--spring .physics-spring-charts__canvas canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.physics-bench--spring .physics-spring-charts__note {
  flex: 0 0 auto;
}

/* Unified outer-glow spotlight (same look in sidebar / stage / chart hosts) */
.physics-spring-spotlight {
  position: absolute;
  inset: 0;
  z-index: 20;
  pointer-events: none;
  overflow: hidden;
}

.physics-spring-spotlight__ring {
  position: absolute;
  border-radius: var(--demo-glow-radius, 12px);
  border: var(--demo-glow-border, 2.5px solid #edd9a0);
  box-shadow:
    var(--demo-glow-ring),
    var(--demo-glow-soft),
    var(--demo-glow-bloom);
  animation: physics-demo-spotlight 1.7s ease-in-out infinite;
}

@keyframes physics-demo-spotlight {
  0%,
  100% {
    box-shadow:
      var(--demo-glow-ring),
      var(--demo-glow-soft),
      var(--demo-glow-bloom);
  }
  50% {
    box-shadow:
      var(--demo-glow-ring-mid),
      var(--demo-glow-soft-mid),
      var(--demo-glow-bloom-mid);
  }
}

@media (prefers-reduced-motion: reduce) {
  .physics-spring-spotlight__ring {
    animation: none;
  }
}

.physics-bench--spring .physics-overlays {
  margin: 0.35rem 0 0;
  padding: 0;
  border: 0;
  min-width: 0;
}

.physics-bench--spring .physics-overlays legend {
  padding: 0;
  margin-bottom: 0.35rem;
}

.physics-field-hint {
  margin: 0.25rem 0 0;
  font-size: 0.7rem;
  line-height: 1.35;
  color: var(--color-muted, #64748b);
}

.physics-slider-scale {
  display: flex;
  justify-content: space-between;
  margin-top: 0.1rem;
  font-size: 0.68rem;
  color: var(--color-muted, #94a3b8);
  font-variant-numeric: tabular-nums;
}

.physics-bench__block + .physics-bench__block {
  padding-top: 0.75rem;
  border-top: 1px solid var(--color-hairline, #e2e8f0);
}

.physics-bench--split2 .physics-bench__block + .physics-bench__block {
  padding-top: 0.9rem;
}

.physics-actions--stepper {
  display: grid;
  grid-template-columns: 2rem minmax(0, 1fr) 2rem;
  gap: 0.35rem;
  align-items: center;
}

.physics-actions--stepper input[type="number"] {
  width: 100%;
  min-width: 0;
  text-align: center;
}

/* Standalone number stepper: always one horizontal row */
.physics-stepper {
  display: grid;
  grid-template-columns: 2.1rem minmax(0, 1fr) 2.1rem;
  align-items: stretch;
  gap: 0;
  width: 100%;
  border: 1px solid var(--color-hairline, #d1d5db);
  border-radius: 8px;
  overflow: hidden;
  background: #fff;
}

.physics-stepper__btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 0;
  min-height: 2rem;
  border: 0;
  border-radius: 0;
  background: #f1f5f9;
  color: var(--color-ink, #0f172a);
  font-size: 1rem;
  font-weight: 650;
  line-height: 1;
  cursor: pointer;
}

.physics-stepper__btn:hover {
  background: #e2e8f0;
}

.physics-stepper__btn:active {
  background: #cbd5e1;
}

.physics-stepper__input {
  width: 100%;
  min-width: 0;
  margin: 0;
  border: 0;
  border-left: 1px solid var(--color-hairline, #d1d5db);
  border-right: 1px solid var(--color-hairline, #d1d5db);
  border-radius: 0;
  background: #fff;
  text-align: center;
  font-size: 0.88rem;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink, #0f172a);
  min-height: 2rem;
  padding: 0.25rem 0.35rem;
}

.physics-stepper__input:focus {
  outline: 2px solid color-mix(in oklab, var(--color-brand, #2260e8) 45%, transparent);
  outline-offset: -2px;
  z-index: 1;
}

.physics-stepper__input::-webkit-outer-spin-button,
.physics-stepper__input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.physics-stepper__input[type="number"] {
  -moz-appearance: textfield;
  appearance: textfield;
}

.physics-actions--toolbar {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 0.4rem;
  margin: 0 0 0.65rem;
}

.physics-actions--toolbar > button {
  width: 100%;
  justify-content: center;
}

.physics-readout--grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.4rem 0.5rem;
}

.physics-readout--grid > div {
  display: grid;
  gap: 0.08rem;
  margin: 0;
  padding: 0.38rem 0.48rem;
  border-radius: 8px;
  background: #fff;
  border: 1px solid rgb(34 96 232 / 12%);
  box-shadow: 0 1px 0 rgb(15 23 42 / 3%);
}

.physics-readout--grid dt {
  margin: 0;
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--color-muted, #64748b);
}

.physics-readout--grid dd {
  margin: 0;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
  font-variant-numeric: tabular-nums;
}

.physics-readout__span2 {
  grid-column: 1 / -1;
}

.physics-bench__controls {
  grid-column: 1;
  grid-row: 1 / -1;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding: 1rem 0.95rem;
  border-right: 1px solid var(--color-hairline, #e2e8f0);
  background: #fafbfc;
  overflow: auto;
}

.physics-bench__stage {
  grid-column: 2;
  grid-row: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
  min-height: 0;
  height: 100%;
  background: #0f1419;
  position: relative;
}

.physics-bench__stage-label {
  position: absolute;
  top: 0.65rem;
  left: 0.75rem;
  z-index: 2;
  margin: 0;
  padding: 0.2rem 0.5rem;
  border-radius: 6px;
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.02em;
  color: #cbd5e1;
  background: rgb(15 20 25 / 55%);
  pointer-events: none;
}

.physics-bench__stage .physics-stage-2d {
  flex: 1;
  min-height: 320px;
  height: 100%;
  border-radius: 0;
}

.physics-bench__chart {
  grid-column: 2;
  grid-row: 2;
  padding: 0.65rem 0.75rem 0.75rem;
  border-top: 1px solid #1e293b;
  background: #0f1419;
}

.physics-bench__chart-title {
  margin: 0 0 0.45rem;
  font-size: 0.75rem;
  font-weight: 650;
  color: #94a3b8;
}

.physics-bench__side {
  grid-column: 3;
  grid-row: 1 / -1;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  padding: 1rem 0.95rem;
  border-left: 1px solid var(--color-hairline, #e2e8f0);
  background: #fff;
  overflow: auto;
}

.physics-section-title {
  margin: 0 0 0.55rem;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-muted, #64748b);
}

.physics-field {
  display: grid;
  gap: 0.28rem;
  margin-bottom: 0.7rem;
  font-size: 0.82rem;
  color: var(--color-body, #334155);
}

.physics-field input[type="number"],
.physics-field input[type="range"] {
  width: 100%;
}

.physics-layer-row,
.physics-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 0.35rem 0 0.55rem;
}

/* Must follow .physics-actions so grid isn't overridden by flex-wrap */
.physics-actions.physics-actions--stepper {
  display: grid;
  grid-template-columns: 2.1rem minmax(0, 1fr) 2.1rem;
  flex-wrap: nowrap;
  gap: 0.35rem;
  align-items: center;
  margin: 0;
}

.physics-actions.physics-actions--toolbar {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  flex-wrap: nowrap;
  align-items: stretch;
  gap: 0.4rem;
  width: 100%;
}

.physics-actions.physics-actions--toolbar > button {
  width: 100%;
  min-width: 0;
  justify-content: center;
  white-space: nowrap;
}

.physics-actions .btn-brand,
.physics-actions .btn-secondary,
.physics-bench__controls .btn-brand,
.physics-bench__controls .btn-secondary {
  font-size: 0.8rem;
  padding: 0.35rem 0.65rem;
}

.physics-check {
  display: inline-flex;
  align-items: center;
  gap: 0.28rem;
  font-size: 0.8rem;
  color: var(--color-body, #334155);
}

.physics-readout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.45rem;
  margin: 0;
}

.physics-readout div {
  background: var(--color-surface-soft, #f8fafc);
  border-radius: 8px;
  padding: 0.4rem 0.5rem;
  border: 1px solid var(--color-hairline, #e2e8f0);
}

.physics-readout dt {
  font-size: 0.68rem;
  font-weight: 650;
  color: var(--color-muted, #64748b);
}

.physics-readout dd {
  margin: 0.12rem 0 0;
  font-size: 0.92rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink, #0f172a);
}

.physics-formula-bar {
  margin-top: 0.35rem;
  padding: 0.55rem 0.6rem;
  border-radius: 8px;
  background: var(--color-surface-soft, #f8fafc);
  border: 1px solid var(--color-hairline, #e2e8f0);
  font-size: 0.88rem;
  color: var(--color-body, #334155);
  overflow-x: auto;
}

.physics-side-note {
  margin: 0;
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--color-body, #475569);
}

.physics-hint {
  margin: 0.45rem 0.75rem 0.65rem;
  font-size: 0.75rem;
  color: #94a3b8;
}

.physics-loading {
  padding: 3rem 1rem;
  text-align: center;
  color: var(--color-muted, #64748b);
}

@media (max-width: 1100px) {
  .physics-bench {
    grid-template-columns: minmax(14rem, 16rem) minmax(0, 1fr);
    grid-template-rows: minmax(280px, 50vh) auto auto;
    min-height: 0;
  }

  .physics-bench__controls {
    grid-column: 1;
    grid-row: 1 / 3;
  }

  .physics-bench__stage {
    grid-column: 2;
    grid-row: 1;
  }

  .physics-bench__chart {
    grid-column: 2;
    grid-row: 2;
  }

  .physics-bench__side {
    grid-column: 1 / -1;
    grid-row: 3;
    border-left: 0;
    border-top: 1px solid var(--color-hairline, #e2e8f0);
    flex-direction: row;
    flex-wrap: wrap;
  }

  .physics-bench__side > * {
    flex: 1 1 14rem;
  }

  .physics-bench--split2 {
    grid-template-columns: 1fr;
    grid-template-rows: auto minmax(280px, 55vh);
  }

  .physics-bench--split2 .physics-bench__controls {
    grid-column: 1;
    grid-row: 1;
    max-height: 42vh;
    border-right: 0;
    border-bottom: 1px solid var(--color-hairline, #e2e8f0);
  }

  .physics-bench--split2 .physics-bench__block--formulas {
    margin-top: 0;
  }

  .physics-bench--split2 .physics-bench__main {
    grid-column: 1;
    grid-row: 2;
    grid-template-rows: minmax(0, 1.1fr) minmax(10rem, 0.9fr);
  }

  .physics-bench--spring {
    grid-template-columns: minmax(16rem, 18.5rem) minmax(0, 1fr);
    grid-template-rows: auto minmax(0, 1fr);
  }

  .physics-bench--no-chart {
    grid-template-rows: minmax(280px, 55vh) auto;
  }

  .physics-bench--no-chart .physics-bench__controls {
    grid-row: 1;
  }

  .physics-bench--no-chart .physics-bench__side {
    grid-row: 2;
  }
}

@media (max-width: 720px) {
  .physics-bench {
    grid-template-columns: 1fr;
    grid-template-rows: auto minmax(260px, 45vh) auto auto;
  }

  .physics-bench__controls,
  .physics-bench__stage,
  .physics-bench__chart,
  .physics-bench__side {
    grid-column: 1;
    grid-row: auto;
    border: 0;
    border-bottom: 1px solid var(--color-hairline, #e2e8f0);
  }

  .physics-bench__controls {
    max-height: none;
  }

  .physics-bench__stage .physics-stage-2d {
    min-height: 260px;
  }

  .physics-bench--split2 {
    grid-template-rows: auto minmax(280px, 50vh);
  }

  .physics-bench--split2 .physics-bench__controls {
    max-height: none;
    border-bottom: 1px solid var(--color-hairline, #e2e8f0);
  }

  .physics-bench--split2 .physics-bench__main {
    border: 0;
    grid-template-rows: minmax(240px, 1fr) minmax(11rem, auto);
  }

  .physics-shell--lab {
    height: auto;
    min-height: calc(100dvh - 64px);
  }

  .physics-bench--spring {
    height: auto;
    min-height: calc(100dvh - 7rem);
    grid-template-columns: 1fr;
    grid-template-rows: auto auto minmax(0, 1fr);
  }

  .physics-bench--spring .physics-bench__toolbar {
    grid-row: 1;
  }

  .physics-bench--spring .physics-bench__sidebar {
    grid-column: 1;
    grid-row: 2;
    border-right: 0;
    border-bottom: 1px solid var(--color-hairline, #e2e8f0);
    max-height: min(48vh, 28rem);
  }

  .physics-bench--spring .physics-bench__main {
    grid-column: 1;
    grid-row: 3;
    min-height: min(70vh, 36rem);
    grid-template-rows: minmax(240px, 1fr) minmax(12rem, 32vh);
  }

  .physics-bench--spring .physics-bench__stage .physics-stage-2d {
    min-height: 220px;
  }

  .physics-bench--spring .physics-spring-demo-card {
    bottom: 0.55rem;
    width: min(26rem, calc(100% - 1rem));
  }
}

/* ?? Electric-field lab (NovaMath brand chrome) ?? */

.physics-eflab {
  display: flex;
  flex-direction: column;
  gap: 0;
  min-height: calc(100dvh - 7.5rem);
  width: 100%;
  border: 1px solid var(--color-hairline, #e5e7eb);
  border-radius: var(--radius-xl, 16px);
  overflow: hidden;
  background: var(--color-canvas, #fff);
  box-shadow: var(--shadow-md, 0 4px 12px rgb(0 0 0 / 0.08));
}

.physics-eflab--focus,
.physics-eflab:fullscreen {
  min-height: 100dvh;
  border-radius: 0;
  border: 0;
}

body.physics-focus-on .landing-header,
body.physics-focus-on .landing-footer,
body.physics-focus-on .physics-topbar,
body.physics-focus-on .physics-labbar,
body.physics-focus-on .physics-about,
body.physics-focus-on .physics-shell--seo {
  display: none !important;
}

body.physics-focus-on .physics-page {
  min-height: 100dvh;
  background: var(--color-surface-soft, #f8f9fa);
}

body.physics-focus-on .physics-shell {
  padding: 0.5rem;
}

/* Single product toolbar: views + actions */
.physics-eflab__bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem 0.75rem;
  padding: 0.45rem 0.7rem;
  border-bottom: 1px solid var(--color-hairline, #e5e7eb);
  background: #fff;
}

.physics-eflab__toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.65rem 1rem;
  padding: 0.7rem 0.9rem;
  border-bottom: 1px solid var(--color-hairline, #e5e7eb);
  background:
    linear-gradient(
      180deg,
      color-mix(in oklab, var(--color-brand, #2260e8) 4%, #fff) 0%,
      #fff 100%
    );
}

.physics-eflab__toolbar-copy {
  min-width: 0;
  flex: 1 1 12rem;
}

.physics-eflab__eyebrow {
  margin: 0 0 0.15rem;
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-brand, #2260e8);
}

.physics-eflab__linked-title {
  margin: 0;
  font-family: var(--font-display, inherit);
  font-size: 1.05rem;
  font-weight: 650;
  letter-spacing: -0.02em;
  color: var(--color-ink, #111);
  line-height: 1.25;
}

.physics-eflab__views {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
  padding: 0.18rem;
  border-radius: 10px;
  background: var(--color-surface-soft, #f8f9fa);
  border: 1px solid var(--color-hairline, #e5e7eb);
}

.physics-eflab__tab {
  border: 1px solid transparent;
  background: transparent;
  color: var(--color-muted, #6b7280);
  font-size: 0.78rem;
  font-weight: 650;
  padding: 0.34rem 0.65rem;
  border-radius: 7px;
  cursor: pointer;
  transition:
    background 0.15s ease,
    color 0.15s ease,
    border-color 0.15s ease;
}

.physics-eflab__tab:hover {
  background: #fff;
  color: var(--color-ink, #111);
}

.physics-eflab__tab.is-active {
  background: #fff;
  border-color: color-mix(in oklab, var(--color-brand, #2260e8) 28%, var(--color-hairline));
  color: var(--color-brand, #2260e8);
  box-shadow: var(--shadow-sm);
}

.physics-eflab__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.3rem;
}

.physics-eflab__actions-sep {
  width: 1px;
  height: 1.1rem;
  margin: 0 0.15rem;
  background: var(--color-hairline, #e5e7eb);
}

.physics-eflab__tools-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  padding: 0.5rem 0.9rem;
  border-bottom: 1px solid var(--color-hairline-soft, #f3f4f6);
  background: #fff;
}

.physics-eflab__tool {
  border: 1px solid var(--color-hairline, #e5e7eb);
  background: #fff;
  color: var(--color-body, #374151);
  font-size: 0.76rem;
  font-weight: 650;
  padding: 0.3rem 0.55rem;
  border-radius: 7px;
  cursor: pointer;
  line-height: 1.2;
}

.physics-eflab__tool:hover {
  border-color: color-mix(in oklab, var(--color-brand) 25%, var(--color-hairline));
  color: var(--color-brand, #2260e8);
}

.physics-eflab__tool.is-active {
  border-color: var(--color-brand, #2260e8);
  color: var(--color-brand, #2260e8);
  background: var(--color-brand-tint, rgb(34 96 232 / 0.08));
}

.physics-eflab__demo {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.55rem;
  padding: 0.55rem 0.9rem;
  background: var(--color-brand-tint, rgb(34 96 232 / 0.08));
  border-bottom: 1px solid color-mix(in oklab, var(--color-brand) 18%, #fff);
  font-size: 0.86rem;
  color: var(--color-ink, #111);
  animation: physics-eflab-demo-in 0.35s ease-out;
}

@keyframes physics-eflab-demo-in {
  from {
    opacity: 0;
    transform: translateY(-6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.physics-eflab__demo p {
  margin: 0;
  flex: 1 1 16rem;
}

.physics-eflab__demo-actions {
  display: flex;
  gap: 0.35rem;
}

.physics-eflab__body {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(16.5rem, 19.5rem);
  min-height: 0;
  flex: 1;
  background: var(--color-surface-soft, #f8f9fa);
}

.physics-eflab__stage {
  position: relative;
  min-height: 440px;
  margin: 0.75rem 0 0.75rem 0.75rem;
  border: 1px solid var(--color-hairline, #e5e7eb);
  border-radius: var(--radius-lg, 12px);
  background: #12161c;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 4%);
}

.physics-eflab__stage .physics-stage-2d {
  flex: 1;
  min-height: 420px;
  height: 100%;
}

.physics-eflab__canvas3d {
  position: relative;
  flex: 1;
  min-height: 420px;
  height: 100%;
  width: 100%;
}

.physics-eflab__canvas3d canvas {
  display: block;
  width: 100% !important;
  height: 100% !important;
}

.physics-eflab__hint {
  position: absolute;
  left: 0.75rem;
  bottom: 0.65rem;
  z-index: 2;
  margin: 0;
  padding: 0.28rem 0.55rem;
  border-radius: 8px;
  font-size: 0.72rem;
  color: #cbd5e1;
  background: rgb(15 20 25 / 72%);
  border: 1px solid rgb(51 65 85 / 55%);
  pointer-events: none;
  backdrop-filter: blur(6px);
}

.physics-eflab__hint--3d {
  z-index: 2;
}

.physics-eflab-3d-tag {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  color: #f8fafc;
  background: rgb(15 23 42 / 78%);
  border: 1px solid rgb(51 65 85 / 70%);
  white-space: nowrap;
  user-select: none;
  box-shadow: 0 1px 2px rgb(0 0 0 / 25%);
}

.physics-eflab-3d-tag--volt {
  color: #93c5fd;
}

.physics-eflab-3d-axis {
  font-size: 11px;
  font-weight: 650;
  color: #94a3b8;
  white-space: nowrap;
}

.physics-eflab__curve {
  position: absolute;
  right: 0.75rem;
  top: 0.75rem;
  z-index: 5;
  width: min(22rem, calc(100% - 1.5rem));
  border-radius: var(--radius-lg, 12px);
  border: 1px solid var(--color-hairline, #e5e7eb);
  background: rgb(255 255 255 / 96%);
  box-shadow: var(--shadow-lg);
  color: var(--color-ink, #111);
  overflow: hidden;
  backdrop-filter: blur(8px);
}

.physics-eflab__curve-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 0.55rem 0.75rem;
  border-bottom: 1px solid var(--color-hairline-soft, #f3f4f6);
  background: linear-gradient(
    180deg,
    color-mix(in oklab, var(--color-brand) 5%, #fff),
    #fff
  );
}

.physics-eflab__curve-head h3 {
  margin: 0;
  font-size: 0.84rem;
  font-weight: 650;
  letter-spacing: -0.01em;
}

.physics-eflab__curve-close {
  border: 0;
  background: transparent;
  color: var(--color-muted, #6b7280);
  font-size: 1.2rem;
  line-height: 1;
  cursor: pointer;
  padding: 0.1rem 0.35rem;
  border-radius: 6px;
}

.physics-eflab__curve-close:hover {
  color: var(--color-brand, #2260e8);
  background: var(--color-brand-tint);
}

.physics-eflab__curve-body {
  padding: 0.35rem 0.55rem 0.15rem;
}

.physics-eflab__curve-canvas {
  width: 100%;
  height: 200px;
  display: block;
  cursor: crosshair;
  border-radius: 8px;
}

.physics-eflab__curve-hover {
  margin: 0.2rem 0 0.35rem;
  font-size: 0.75rem;
  color: var(--color-brand, #2260e8);
  font-variant-numeric: tabular-nums;
  font-weight: 650;
}

.physics-eflab__curve-note {
  margin: 0;
  padding: 0.45rem 0.75rem 0.65rem;
  font-size: 0.72rem;
  line-height: 1.45;
  color: var(--color-muted, #6b7280);
  border-top: 1px solid var(--color-hairline-soft, #f3f4f6);
}

.physics-eflab__curve-actions {
  display: flex;
  gap: 0.35rem;
  padding: 0 0.75rem 0.55rem;
}

.physics-eflab__side {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
  padding: 0.7rem 0.75rem 0.8rem 0.55rem;
  overflow: auto;
}

.physics-eflab__card {
  padding: 0.7rem 0.75rem;
  border-radius: var(--radius-lg, 12px);
  border: 1px solid var(--color-hairline, #e5e7eb);
  background: #fff;
  box-shadow: var(--shadow-sm);
}

.physics-eflab__card--formulas .physics-eflab__formulas {
  flex-direction: column;
}

.physics-readout--accent dd {
  color: var(--color-brand, #2260e8);
}

.physics-eflab__footer {
  border-top: 1px solid var(--color-hairline, #e5e7eb);
  padding: 0.75rem 0.95rem 0.9rem;
  background: #fff;
}

.physics-eflab__formulas {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.physics-eflab__formulas .physics-formula-bar {
  margin: 0;
  flex: 1 1 12rem;
}

.physics-eflab__card--formulas .physics-eflab__formulas .physics-formula-bar {
  flex: 1 1 auto;
}

.physics-eflab__footnote {
  margin: 0.5rem 0 0;
  font-size: 0.72rem;
  line-height: 1.45;
  color: var(--color-muted, #6b7280);
}

.physics-eflab__modal {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  place-items: center;
  padding: 1rem;
}

.physics-eflab__modal-backdrop {
  position: absolute;
  inset: 0;
  border: 0;
  background: rgb(17 17 17 / 35%);
  cursor: pointer;
}

.physics-eflab__modal-card {
  position: relative;
  z-index: 1;
  width: min(32rem, 100%);
  max-height: min(80dvh, 40rem);
  overflow: auto;
  border-radius: var(--radius-xl, 16px);
  background: #fff;
  padding: 1.1rem 1.15rem 1.2rem;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--color-hairline, #e5e7eb);
}

.physics-eflab__modal-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.physics-eflab__modal-head h2 {
  margin: 0;
  font-family: var(--font-display, inherit);
  font-size: 1.15rem;
  letter-spacing: -0.02em;
}

.physics-eflab__guide-list {
  margin: 0;
  padding-left: 1.15rem;
  display: grid;
  gap: 0.55rem;
  font-size: 0.9rem;
  line-height: 1.5;
  color: var(--color-body, #374151);
}

@media (max-width: 960px) {
  .physics-eflab__bar,
  .physics-eflab__toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  .physics-eflab__actions {
    justify-content: flex-start;
  }

  .physics-eflab__body {
    grid-template-columns: 1fr;
  }

  .physics-eflab__stage {
    margin: 0.65rem 0.65rem 0;
  }

  .physics-eflab__side {
    padding: 0.65rem;
  }

  .physics-eflab__side {
    border-top: 0;
  }

  .physics-eflab__stage,
  .physics-eflab__stage .physics-stage-2d,
  .physics-eflab__canvas3d {
    min-height: 340px;
  }

  .physics-eflab__curve {
    position: relative;
    right: auto;
    top: auto;
    width: 100%;
    border-radius: 0;
    border-left: 0;
    border-right: 0;
    box-shadow: none;
  }
}


/* ?? Physics Lab hub (/physics.html) ?? */

.physics-hub {
  --ph-ink: #0b1220;
  --ph-muted: #64748b;
  --ph-line: color-mix(in oklab, #2260e8 12%, #e2e8f0);
  background: #f7f8fb;
  color: var(--ph-ink);
}

.physics-hub__wrap {
  width: 100%;
  max-width: 72rem;
  margin-inline: auto;
  padding-inline: 1.15rem;
  box-sizing: border-box;
}

@media (min-width: 1024px) {
  .physics-hub__wrap {
    padding-inline: 1.75rem;
  }
}

/* Hero ? one composition, brand first */
.physics-hub__hero {
  position: relative;
  isolation: isolate;
  min-height: 0;
  display: flex;
  align-items: flex-end;
  overflow: hidden;
  background:
    radial-gradient(ellipse 80% 60% at 70% 20%, rgb(34 96 232 / 0.16), transparent 55%),
    radial-gradient(ellipse 50% 40% at 10% 80%, rgb(91 155 255 / 0.1), transparent 50%),
    linear-gradient(165deg, #eef3ff 0%, #f7f8fb 42%, #fbfbfc 100%);
}

.physics-hub__hero-visual {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}

.physics-hub__field {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  opacity: 0.9;
  animation: physics-hub-field-in 1.2s ease-out both;
}

.physics-hub__hero-glow {
  position: absolute;
  width: 36%;
  height: 70%;
  right: 6%;
  top: -10%;
  border-radius: 50%;
  background: radial-gradient(circle, rgb(91 155 255 / 0.2), transparent 68%);
  filter: blur(8px);
  animation: physics-hub-glow 8s ease-in-out infinite alternate;
}

.physics-hub__hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgb(15 23 42 / 0.035) 1px, transparent 1px),
    linear-gradient(90deg, rgb(15 23 42 / 0.035) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 70% 65% at 65% 40%, #000 20%, transparent 75%);
  opacity: 0.7;
}

.physics-hub__hero-inner {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 72rem;
  margin-inline: auto;
  padding: 2rem 1.15rem 1.65rem;
  box-sizing: border-box;
  animation: physics-hub-rise 0.85s cubic-bezier(0.22, 1, 0.36, 1) both;
}

@media (min-width: 1024px) {
  .physics-hub__hero-inner {
    padding: 2.35rem 1.75rem 1.85rem;
  }
}

.physics-hub__brand {
  margin: 0 0 0.35rem;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.65rem, 3.4vw, 2.35rem);
  font-weight: 750;
  letter-spacing: -0.045em;
  line-height: 0.95;
  color: var(--color-brand, #2260e8);
}

.physics-hub__title {
  margin: 0;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.15rem, 2vw, 1.45rem);
  font-weight: 650;
  letter-spacing: -0.03em;
  line-height: 1.15;
  color: var(--ph-ink);
}

.physics-hub__lead {
  margin: 0.55rem 0 0;
  max-width: 32rem;
  font-size: 0.95rem;
  line-height: 1.55;
  color: var(--ph-muted);
}

/* Featured (legacy / GeoGebra suite reuse) */
.physics-hub__featured {
  padding: 2.75rem 0 2.35rem;
  background: #fff;
  border-top: 1px solid var(--ph-line);
}

.physics-hub__catalog {
  padding: 2.75rem 0 4.5rem;
  background: #f7f8fb;
}

/* Experiment lab list — grouped by topic for crawlable pillar content */
.physics-hub__labs {
  padding: 0.85rem 0 4.5rem;
  background: #fff;
  border-top: 1px solid var(--ph-line);
}

.physics-hub__topics {
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
}

.physics-hub__topic[hidden] {
  display: none;
}

.physics-hub__topic-head {
  margin: 0 0 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--ph-line);
  scroll-margin-top: 7.5rem;
}

.physics-hub__topic-title {
  margin: 0;
  font-size: clamp(1.2rem, 1.5vw, 1.45rem);
  font-weight: 780;
  letter-spacing: -0.02em;
  color: #0f172a;
}

.physics-hub__topic-desc {
  margin: 0.4rem 0 0;
  max-width: 40rem;
  font-size: 0.92rem;
  line-height: 1.55;
  color: #64748b;
}

.physics-hub__topic-title a {
  color: inherit;
  text-decoration: none;
}

.physics-hub__topic-title a:hover {
  color: var(--color-brand, #2260e8);
}

.physics-hub__topic-more {
  margin: 0.55rem 0 0;
}

.physics-hub__topic-more a {
  font-size: 0.88rem;
  font-weight: 650;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-hub__topic-more a:hover {
  text-decoration: underline;
}

.physics-hub__hero--compact {
  min-height: auto;
  padding: 2.5rem 0 2rem;
}

.physics-hub__crumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  align-items: center;
  margin: 0 0 1rem;
  font-size: 0.84rem;
  color: #94a3b8;
}

.physics-hub__crumbs a {
  color: #64748b;
  text-decoration: none;
}

.physics-hub__crumbs a:hover {
  color: var(--color-brand, #2260e8);
}

.physics-hub__module-count {
  margin: 0.85rem 0 0;
  font-size: 0.9rem;
  font-weight: 650;
  color: #64748b;
}

.physics-hub__feature-tags {
  display: block;
  margin-top: 0.35rem;
  font-size: 0.78rem;
  font-weight: 600;
  color: #94a3b8;
}

.physics-hub__exp-badge--ready {
  background: color-mix(in oklab, #2260e8 12%, #fff);
  color: #2260e8;
}

.physics-hub__pillar-seo {
  padding: 0 0 0.5rem;
}

.physics-hub__pillar-seo .physics-hub__wrap {
  padding-top: 0.25rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--ph-line);
}

.physics-hub__pillar-prose {
  margin: 0.65rem 0 0;
  max-width: 46rem;
  line-height: 1.7;
  color: #334155;
  font-size: 0.98rem;
}

.physics-hub__pillar-sub {
  margin: 1.35rem 0 0.5rem;
  font-size: 1rem;
  font-weight: 700;
  color: #0f172a;
}

.physics-hub__pillar-list {
  margin: 0.35rem 0 0;
  padding-left: 1.2rem;
  max-width: 42rem;
  color: #334155;
  line-height: 1.55;
}

.physics-hub__pillar-list li + li {
  margin-top: 0.3rem;
}

.physics-hub__pillar-formulas {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0.75rem;
  margin: 0.5rem 0 0;
  padding: 0;
  list-style: none;
}

.physics-hub__pillar-formulas code {
  display: inline-block;
  padding: 0.35rem 0.65rem;
  border-radius: 6px;
  background: color-mix(in oklab, #2260e8 8%, #fff);
  font-size: 0.9rem;
  color: #0f172a;
}

.physics-hub__pillar-faq {
  margin: 0.5rem 0 0;
  max-width: 46rem;
}

.physics-hub__pillar-faq dt {
  margin-top: 0.85rem;
  font-weight: 650;
  color: #0f172a;
}

.physics-hub__pillar-faq dt:first-child,
.physics-hub__pillar-faq > div:first-child dt {
  margin-top: 0;
}

.physics-hub__pillar-faq dd {
  margin: 0.3rem 0 0;
  color: #475569;
  line-height: 1.6;
}

.physics-hub__cluster {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem 1.15rem;
  margin-top: 1.5rem;
}

.physics-hub__cluster a {
  font-size: 0.92rem;
  font-weight: 650;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-hub__cluster a:hover {
  text-decoration: underline;
}

.physics-hub__related {
  margin-top: 2.75rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--ph-line);
}

.physics-hub__related-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
  margin: 0.85rem 0 0;
  padding: 0;
  list-style: none;
}

.physics-hub__related-list a {
  font-size: 0.92rem;
  font-weight: 650;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-hub__related-list a:hover {
  text-decoration: underline;
}

.physics-hub__back {
  margin: 2rem 0 0;
}

.physics-hub__back a {
  font-size: 0.92rem;
  font-weight: 650;
  color: #475569;
  text-decoration: none;
}

.physics-hub__back a:hover {
  color: var(--color-brand, #2260e8);
}

.physics-hub__toolbar {
  position: sticky;
  top: 64px;
  z-index: 25;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  margin: 0 0 1.25rem;
  padding: 0.75rem 0 0.7rem;
  background: color-mix(in oklab, #fff 92%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--ph-line);
}

@media (min-width: 1024px) {
  .physics-hub__toolbar {
    top: 72px;
  }
}

.physics-hub__toolbar-top {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  min-width: 0;
}

.physics-hub__toolbar-top .physics-hub__search {
  flex: 1 1 auto;
}

.physics-hub__toolbar-top .physics-hub__toolbar-count {
  margin: 0;
}

.physics-hub__search {
  position: relative;
  display: block;
  width: 100%;
  max-width: 28rem;
}

.physics-hub__topic {
  scroll-margin-top: 9.5rem;
}

.physics-hub__search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  width: 1rem;
  height: 1rem;
  transform: translateY(-50%);
  color: #94a3b8;
  pointer-events: none;
}

.physics-hub__search input {
  appearance: none;
  width: 100%;
  box-sizing: border-box;
  margin: 0;
  padding: 0.55rem 0.85rem 0.55rem 2.15rem;
  border: 1px solid var(--ph-line);
  border-radius: 999px;
  background: #f7f8fb;
  color: var(--ph-ink);
  font-size: 0.9rem;
  line-height: 1.3;
  outline: none;
  transition:
    border-color 0.15s ease,
    background 0.15s ease,
    box-shadow 0.15s ease;
}

.physics-hub__search input::placeholder {
  color: #94a3b8;
}

.physics-hub__search input:hover {
  border-color: color-mix(in oklab, var(--color-brand, #2260e8) 28%, #e2e8f0);
}

.physics-hub__search input:focus {
  border-color: color-mix(in oklab, var(--color-brand, #2260e8) 45%, #e2e8f0);
  background: #fff;
  box-shadow: 0 0 0 3px rgb(34 96 232 / 0.12);
}

.physics-hub__search:focus-within .physics-hub__search-icon {
  color: var(--color-brand, #2260e8);
}

.physics-hub__filter-stack {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  min-width: 0;
}

.physics-hub__filter-row {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  min-width: 0;
}

.physics-hub__toolbar-count {
  flex: 0 0 auto;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--ph-muted);
  white-space: nowrap;
  font-variant-numeric: tabular-nums;
}

.physics-hub__chip-scroller {
  flex: 1 1 auto;
  min-width: 0;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: thin;
  mask-image: linear-gradient(
    90deg,
    #000 0,
    #000 calc(100% - 1.5rem),
    transparent 100%
  );
}

.physics-hub__chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.28rem;
  width: 100%;
  padding: 0;
}

.physics-hub__chips--level {
  flex-wrap: wrap;
}

.physics-hub__chips--topics {
  flex-wrap: nowrap;
  width: max-content;
  min-width: 100%;
  padding-right: 1.25rem;
}

.physics-hub__chips--topics .physics-hub__chip[hidden] {
  display: none;
}

.physics-hub__chip {
  appearance: none;
  flex: 0 0 auto;
  margin: 0;
  padding: 0.36rem 0.68rem;
  border: 1px solid transparent;
  border-radius: 999px;
  background: transparent;
  color: var(--ph-muted);
  font-size: 0.8rem;
  font-weight: 650;
  line-height: 1.2;
  white-space: nowrap;
  cursor: pointer;
  transition:
    color 0.15s ease,
    border-color 0.15s ease,
    background 0.15s ease;
}

.physics-hub__chip:hover {
  color: var(--ph-ink);
  background: rgb(15 23 42 / 0.035);
}

.physics-hub__chip:focus-visible {
  outline: 2px solid var(--color-brand, #2260e8);
  outline-offset: 2px;
}

.physics-hub__chip.is-active {
  color: var(--color-brand, #2260e8);
  border-color: color-mix(in oklab, var(--color-brand, #2260e8) 28%, #e2e8f0);
  background: color-mix(in oklab, var(--color-brand, #2260e8) 9%, #fff);
}

/* Curriculum toggle sits with level chips, visually separated */
.physics-hub__chip--required {
  margin-left: 0.35rem;
  position: relative;
}

.physics-hub__chip--required::before {
  content: "";
  position: absolute;
  left: -0.35rem;
  top: 20%;
  bottom: 20%;
  width: 1px;
  background: color-mix(in oklab, var(--ph-muted) 40%, transparent);
}

.physics-hub__exp-grid {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem;
  align-items: stretch;
}

.physics-hub__exp-grid > li[hidden] {
  display: none;
}

.physics-hub__exp-module {
  display: block;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: color-mix(in oklab, var(--color-brand, #2260e8) 55%, #94a3b8);
}

.physics-hub__feature-body {
  display: flex;
  flex-direction: column;
  gap: 0.28rem;
  flex: 1 1 auto;
  min-width: 0;
}

.physics-hub__exp-badge {
  display: inline-flex;
  align-self: flex-start;
  margin-top: 0.15rem;
  padding: 0.18rem 0.5rem;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 700;
  color: #64748b;
  background: #f1f5f9;
}

.physics-hub__feature.is-disabled {
  cursor: default;
  opacity: 0.78;
}

.physics-hub__feature.is-disabled:hover {
  transform: none;
  border-color: var(--ph-line);
  box-shadow: none;
}

.physics-hub__empty {
  margin: 2rem 0 0;
  text-align: center;
  font-size: 0.95rem;
  color: var(--ph-muted);
}

@media (max-width: 980px) {
  .physics-hub__exp-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .physics-hub__exp-grid {
    grid-template-columns: 1fr;
  }

  .physics-hub__toolbar {
    top: 56px;
  }

  .physics-hub__search {
    max-width: none;
  }

  .physics-hub__toolbar-top {
    flex-wrap: wrap;
  }

  .physics-hub__topic {
    scroll-margin-top: 11rem;
  }
}

.physics-hub__section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 0.75rem 1.5rem;
  margin-bottom: 1.75rem;
}

.physics-hub__feature-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: end;
  column-gap: 1.25rem;
  margin-bottom: 1.35rem;
}

.physics-hub__feature-head-copy {
  min-width: 0;
}

.physics-hub__feature-note {
  margin: 0;
  padding-bottom: 0.28rem;
  font-size: 0.86rem;
  font-weight: 650;
  color: var(--ph-muted);
  white-space: nowrap;
}

.physics-hub__eyebrow {
  margin: 0 0 0.4rem;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-brand, #2260e8);
}

.physics-hub__h2 {
  margin: 0;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.45rem, 2.4vw, 1.85rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--ph-ink);
}

.physics-hub__section-desc {
  margin: 0.55rem 0 0;
  font-size: 0.95rem;
  color: var(--ph-muted);
}

.physics-hub__mvp-hint {
  margin: 0.4rem 0 0;
  max-width: 42rem;
  font-size: 0.84rem;
  line-height: 1.45;
  color: #92400e;
}

.physics-hub__section-note {
  margin: 0;
  font-size: 0.88rem;
  font-weight: 650;
  color: var(--ph-muted);
}

.physics-hub__feature-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1rem;
  align-items: stretch;
}

@media (max-width: 1100px) {
  .physics-hub__feature-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.physics-hub__feature-item {
  min-width: 0;
  display: flex;
}

.physics-hub__feature {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 0.65rem;
  width: 100%;
  min-height: 100%;
  box-sizing: border-box;
  padding: 0.9rem 0.95rem 1rem;
  text-decoration: none;
  color: inherit;
  border: 1px solid var(--ph-line);
  border-radius: 14px;
  background:
    linear-gradient(135deg, rgb(34 96 232 / 0.04), transparent 42%),
    #fff;
  transition:
    transform 0.25s cubic-bezier(0.22, 1, 0.36, 1),
    border-color 0.2s ease,
    box-shadow 0.25s ease;
}

.physics-hub__feature:hover {
  transform: translateY(-2px);
  border-color: color-mix(in oklab, var(--color-brand, #2260e8) 35%, #e2e8f0);
  box-shadow: 0 14px 36px rgb(15 23 42 / 0.08);
}

.physics-hub__feature-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.physics-hub__feature-index {
  font-family: var(--font-display, inherit);
  font-size: 0.95rem;
  font-weight: 750;
  letter-spacing: 0.04em;
  color: var(--color-brand, #2260e8);
  line-height: 1;
}

.physics-hub__feature-go {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--color-brand, #2260e8);
  white-space: nowrap;
  line-height: 1;
}

.physics-hub__feature-art {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 10;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: 0 4px 14px rgb(15 23 42 / 0.06);
}

.physics-hub__feature-art svg {
  display: block;
  width: 100%;
  height: 100%;
}

.physics-hub__feature-title {
  display: block;
  font-family: var(--font-display, inherit);
  font-size: 1.02rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.3;
  color: var(--ph-ink);
}

.physics-hub__feature-desc {
  display: -webkit-box;
  margin: 0;
  font-size: 0.84rem;
  line-height: 1.45;
  color: var(--ph-muted);
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

@media (max-width: 720px) {
  .physics-hub__feature-list {
    grid-template-columns: 1fr;
  }

  .physics-hub__feature-head {
    grid-template-columns: 1fr;
    align-items: start;
    gap: 0.45rem;
  }

  .physics-hub__feature-note {
    padding-bottom: 0;
  }

  .physics-hub__feature-title {
    min-height: 0;
  }
}

/* GeoGebra hub extras (shares physics-hub shell) */
.gg-hub__suite-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-top: 0.15rem;
}

.gg-hub__suite-chip {
  padding: 0.18rem 0.45rem;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 650;
  color: var(--color-brand, #2260e8);
  background: rgb(34 96 232 / 0.08);
  max-width: 100%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Module catalog ? editorial index, not card farm */
.physics-hub__modules {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--ph-line);
}

.physics-hub__module {
  display: grid;
  grid-template-columns: 2.75rem 7.5rem minmax(0, 1fr) auto auto;
  align-items: center;
  gap: 0.85rem 1rem;
  padding: 0.95rem 0.35rem;
  text-decoration: none;
  color: inherit;
  border-bottom: 1px solid var(--ph-line);
  transition:
    background 0.2s ease,
    padding-left 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}

.physics-hub__module:hover {
  background: rgb(34 96 232 / 0.035);
  padding-left: 0.55rem;
}

.physics-hub__module-art {
  display: block;
  width: 7.5rem;
  height: 4.7rem;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 6px 18px rgb(15 23 42 / 0.06);
  transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1);
}

.physics-hub__module-art svg {
  display: block;
  width: 100%;
  height: 100%;
}

.physics-hub__module:hover .physics-hub__module-art {
  transform: scale(1.03);
}

.physics-hub__module-num {
  font-family: var(--font-display, inherit);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: color-mix(in oklab, var(--color-brand, #2260e8) 40%, #94a3b8);
}

.physics-hub__module-main {
  display: flex;
  flex-direction: column;
  gap: 0.28rem;
  min-width: 0;
}

.physics-hub__module-title {
  font-family: var(--font-display, inherit);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ph-ink);
}

.physics-hub__module-desc {
  font-size: 0.86rem;
  line-height: 1.45;
  color: var(--ph-muted);
  display: -webkit-box;
  -webkit-line-clamp: 1;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.physics-hub__module-meta {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.25rem;
  text-align: right;
}

.physics-hub__module-count {
  font-size: 0.78rem;
  font-weight: 650;
  color: var(--ph-muted);
}

.physics-hub__module-status {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: #94a3b8;
}

.physics-hub__module-status.is-live {
  color: var(--color-brand, #2260e8);
}

.physics-hub__module-arrow {
  font-size: 1.05rem;
  color: color-mix(in oklab, var(--color-brand, #2260e8) 50%, #94a3b8);
  transition: transform 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}

.physics-hub__module:hover .physics-hub__module-arrow {
  transform: translateX(4px);
  color: var(--color-brand, #2260e8);
}

@keyframes physics-hub-rise {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes physics-hub-field-in {
  from {
    opacity: 0;
    transform: scale(1.04);
  }
  to {
    opacity: 0.9;
    transform: scale(1);
  }
}

@keyframes physics-hub-glow {
  from {
    transform: translate3d(0, 0, 0) scale(1);
    opacity: 0.75;
  }
  to {
    transform: translate3d(-18px, 12px, 0) scale(1.08);
    opacity: 1;
  }
}

@media (max-width: 720px) {
  .physics-hub__module {
    grid-template-columns: 2.2rem minmax(0, 1fr) auto;
    grid-template-areas:
      "num art arrow"
      "num main arrow"
      "num meta arrow";
  }

  .physics-hub__module-num {
    grid-area: num;
    align-self: start;
    padding-top: 0.35rem;
  }

  .physics-hub__module-art {
    grid-area: art;
    width: 100%;
    max-width: 11rem;
    height: auto;
    aspect-ratio: 16 / 10;
  }

  .physics-hub__module-main {
    grid-area: main;
  }

  .physics-hub__module-meta {
    grid-area: meta;
    flex-direction: row;
    align-items: center;
    justify-content: flex-start;
    gap: 0.55rem;
    text-align: left;
  }

  .physics-hub__module-arrow {
    grid-area: arrow;
  }

  .physics-hub__module-desc {
    -webkit-line-clamp: 2;
  }
}

@media (prefers-reduced-motion: reduce) {
  .physics-hub__field,
  .physics-hub__hero-inner,
  .physics-hub__hero-glow,
  .physics-hub__feature,
  .physics-hub__module,
  .physics-hub__module-arrow {
    animation: none !important;
    transition: none !important;
  }

  .physics-hub__toolbar {
    backdrop-filter: none;
    background: #fff;
  }
}

/* ?? Physics module directory page ?? */

.physics-mod__hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: 3.25rem 0 2.75rem;
  background:
    radial-gradient(ellipse 70% 80% at 88% 0%, rgb(34 96 232 / 0.14), transparent 55%),
    linear-gradient(180deg, #eef3ff 0%, #f7f8fb 100%);
  border-bottom: 1px solid var(--ph-line, color-mix(in oklab, #2260e8 12%, #e2e8f0));
}

.physics-mod__hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgb(15 23 42 / 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgb(15 23 42 / 0.03) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: linear-gradient(90deg, transparent, #000 35%, #000 75%, transparent);
  opacity: 0.65;
}

.physics-mod__hero-inner {
  position: relative;
  z-index: 1;
  animation: physics-hub-rise 0.75s cubic-bezier(0.22, 1, 0.36, 1) both;
}

.physics-mod__hero-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(10rem, 14rem);
  gap: 1.5rem 2rem;
  align-items: end;
}

.physics-mod__hero-art {
  width: 100%;
  max-width: 14rem;
  justify-self: end;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 16px 40px rgb(15 23 42 / 0.1);
}

.physics-mod__hero-art svg {
  display: block;
  width: 100%;
  height: auto;
}

@media (max-width: 720px) {
  .physics-mod__hero-row {
    grid-template-columns: 1fr;
  }

  .physics-mod__hero-art {
    justify-self: start;
    max-width: 12rem;
  }
}

.physics-mod__crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.35rem;
  margin: 0 0 1.35rem;
  font-size: 0.82rem;
  color: var(--ph-muted, #64748b);
}

.physics-mod__crumbs a {
  color: inherit;
  text-decoration: none;
}

.physics-mod__crumbs a:hover {
  color: var(--color-brand, #2260e8);
  text-decoration: underline;
}

.physics-mod__brand {
  margin: 0 0 0.55rem;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.55rem, 3.5vw, 2.35rem);
  font-weight: 750;
  letter-spacing: -0.04em;
  line-height: 1;
  color: var(--color-brand, #2260e8);
}

.physics-mod__kicker {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.55rem 0.85rem;
  margin: 0 0 0.65rem;
  font-size: 0.86rem;
  font-weight: 650;
  color: var(--ph-muted, #64748b);
}

.physics-mod__kicker-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.4rem;
  padding: 0.18rem 0.45rem;
  border-radius: 7px;
  font-family: var(--font-display, inherit);
  font-size: 0.78rem;
  font-weight: 750;
  letter-spacing: 0.06em;
  color: var(--color-brand, #2260e8);
  background: rgb(34 96 232 / 0.1);
}

.physics-mod__title {
  margin: 0;
  max-width: 40rem;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.65rem, 3.4vw, 2.45rem);
  font-weight: 700;
  letter-spacing: -0.035em;
  line-height: 1.15;
  color: var(--ph-ink, #0b1220);
}

.physics-mod__lead {
  margin: 0.85rem 0 0;
  max-width: 36rem;
  font-size: 1.02rem;
  line-height: 1.6;
  color: var(--ph-muted, #64748b);
}

.physics-mod__list {
  padding: 2.5rem 0 4rem;
  background: #fff;
}

.physics-mod__experiments {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--ph-line, color-mix(in oklab, #2260e8 12%, #e2e8f0));
}

.physics-mod__exp {
  display: grid;
  grid-template-columns: 2.75rem 7.25rem minmax(0, 1fr) auto;
  align-items: center;
  gap: 0.85rem 1rem;
  padding: 0.85rem 0.4rem;
  text-decoration: none;
  color: inherit;
  border-bottom: 1px solid var(--ph-line, color-mix(in oklab, #2260e8 12%, #e2e8f0));
  transition:
    background 0.2s ease,
    padding-left 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}

a.physics-mod__exp.is-live:hover {
  background: rgb(34 96 232 / 0.035);
  padding-left: 0.55rem;
}

a.physics-mod__exp.is-live:hover .physics-mod__exp-art {
  transform: scale(1.03);
}

.physics-mod__exp.is-soon {
  opacity: 0.72;
  cursor: default;
}

.physics-mod__exp-art {
  display: block;
  width: 7.25rem;
  height: 4.55rem;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: 0 6px 18px rgb(15 23 42 / 0.06);
  transition: transform 0.3s cubic-bezier(0.22, 1, 0.36, 1);
}

.physics-mod__exp-art svg {
  display: block;
  width: 100%;
  height: 100%;
}

.physics-mod__exp-num {
  font-family: var(--font-display, inherit);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: color-mix(in oklab, var(--color-brand, #2260e8) 40%, #94a3b8);
}

.physics-mod__exp.is-live .physics-mod__exp-num {
  color: var(--color-brand, #2260e8);
}

.physics-mod__exp-main {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  min-width: 0;
}

.physics-mod__exp-title {
  font-family: var(--font-display, inherit);
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ph-ink, #0b1220);
}

.physics-mod__exp-desc {
  font-size: 0.88rem;
  line-height: 1.5;
  color: var(--ph-muted, #64748b);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.physics-mod__exp-status {
  font-size: 0.8rem;
  font-weight: 700;
  color: #94a3b8;
  white-space: nowrap;
}

.physics-mod__exp-status.is-live {
  color: var(--color-brand, #2260e8);
}

@media (max-width: 720px) {
  .physics-mod__exp {
    grid-template-columns: 2.2rem minmax(0, 1fr) auto;
    grid-template-areas:
      "num art status"
      "num main status";
  }

  .physics-mod__exp-num {
    grid-area: num;
    align-self: start;
    padding-top: 0.35rem;
  }

  .physics-mod__exp-art {
    grid-area: art;
    width: 100%;
    max-width: 10.5rem;
    height: auto;
    aspect-ratio: 16 / 10;
  }

  .physics-mod__exp-main {
    grid-area: main;
  }

  .physics-mod__exp-status {
    grid-area: status;
    align-self: start;
    padding-top: 0.35rem;
  }
}

.physics-mod__pager {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 0.85rem 1rem;
  align-items: stretch;
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--ph-line, color-mix(in oklab, #2260e8 12%, #e2e8f0));
}

.physics-mod__pager-link {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  min-width: 0;
  padding: 0.95rem 1.05rem;
  text-decoration: none;
  color: inherit;
  border: 1px solid var(--ph-line, color-mix(in oklab, #2260e8 12%, #e2e8f0));
  border-radius: 12px;
  background: #f7f8fb;
  transition:
    border-color 0.2s ease,
    background 0.2s ease,
    transform 0.25s cubic-bezier(0.22, 1, 0.36, 1);
}

.physics-mod__pager-link:not(.is-empty):hover {
  border-color: color-mix(in oklab, var(--color-brand, #2260e8) 35%, #e2e8f0);
  background: #fff;
  transform: translateY(-2px);
}

.physics-mod__pager-link.is-next {
  text-align: right;
  justify-self: end;
}

.physics-mod__pager-link.is-empty {
  border: 0;
  background: transparent;
  pointer-events: none;
}

.physics-mod__pager-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ph-muted, #64748b);
}

.physics-mod__pager-title {
  font-family: var(--font-display, inherit);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ph-ink, #0b1220);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.physics-mod__pager-hub {
  align-self: center;
  padding: 0.55rem 0.9rem;
  font-size: 0.84rem;
  font-weight: 700;
  text-decoration: none;
  color: var(--color-brand, #2260e8);
  border-radius: 999px;
  border: 1px solid color-mix(in oklab, var(--color-brand, #2260e8) 28%, #e2e8f0);
  background: #fff;
  white-space: nowrap;
}

.physics-mod__pager-hub:hover {
  background: rgb(34 96 232 / 0.06);
}

@media (max-width: 720px) {
  .physics-mod__pager {
    grid-template-columns: 1fr;
  }

  .physics-mod__pager-link.is-next {
    text-align: left;
    justify-self: stretch;
  }

  .physics-mod__pager-hub {
    order: -1;
    justify-self: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  .physics-mod__hero-inner,
  .physics-mod__exp,
  .physics-mod__pager-link {
    animation: none !important;
    transition: none !important;
  }
}

/* ?? Spring oscillator extras ?? */

.physics-spring-hint {
  position: absolute;
  left: 0.75rem;
  bottom: 0.55rem;
  z-index: 2;
  margin: 0;
  padding: 0.2rem 0.5rem;
  border-radius: 6px;
  font-size: 0.72rem;
  font-weight: 600;
  color: #94a3b8;
  background: rgb(15 20 25 / 55%);
  pointer-events: none;
}

.physics-spring-formulas {
  position: absolute;
  z-index: 5;
  top: 0.55rem;
  right: 0.55rem;
  left: auto;
  --drag-x: 0px;
  --drag-y: 0px;
  transform: translate(var(--drag-x), var(--drag-y));
  width: min(22.5rem, calc(100% - 1.1rem));
  max-height: calc(100% - 1.2rem);
  display: flex;
  flex-direction: column;
  border-radius: 12px;
  border: 1px solid rgb(148 163 184 / 28%);
  background: rgb(15 23 32 / 92%);
  box-shadow: 0 12px 32px rgb(0 0 0 / 35%);
  backdrop-filter: blur(10px);
  color: #e2e8f0;
  overflow: hidden;
  touch-action: none;
}

.physics-spring-formulas__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  padding: 0.55rem 0.7rem 0.4rem;
  border-bottom: 1px solid rgb(148 163 184 / 18%);
  flex: 0 0 auto;
}

.physics-spring-formulas__head h3 {
  margin: 0;
  flex: 1 1 auto;
  font-size: 0.82rem;
  font-weight: 700;
  color: #f8fafc;
}

.physics-spring-drag-handle {
  cursor: grab;
  user-select: none;
  touch-action: none;
}

.physics-spring-drag-handle:active {
  cursor: grabbing;
}

.physics-spring-drag-grip {
  flex: 0 0 auto;
  font-size: 0.7rem;
  letter-spacing: -0.12em;
  color: #64748b;
  line-height: 1;
  opacity: 0.85;
}

.physics-spring-formulas .physics-spring-drag-grip {
  color: #94a3b8;
}

.physics-spring-formulas__close {
  width: 1.6rem;
  height: 1.6rem;
  border: 0;
  border-radius: 6px;
  background: transparent;
  color: #94a3b8;
  font-size: 1.15rem;
  line-height: 1;
  cursor: pointer;
}

.physics-spring-formulas__close:hover {
  background: rgb(148 163 184 / 18%);
  color: #e2e8f0;
}

.physics-spring-formulas__body {
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  padding: 0.35rem 0.7rem 0.7rem;
}

.physics-spring-formulas__sec {
  margin: 0;
  padding: 0.45rem 0;
  border-bottom: 1px solid rgb(148 163 184 / 14%);
}

.physics-spring-formulas__sec h4 {
  margin: 0 0 0.3rem;
  font-size: 0.72rem;
  font-weight: 650;
  color: #94a3b8;
  letter-spacing: 0.02em;
}

.physics-spring-formulas__eq {
  margin: 0;
  font-size: 0.95rem;
  color: #f1f5f9;
  overflow-x: auto;
}

.physics-spring-formulas__eq .katex {
  font-size: 1.05em;
}

.physics-spring-formulas__sec--live {
  border-bottom: 0;
}

.physics-spring-formulas__live-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem;
}

.physics-spring-formulas__E {
  font-size: 1.05rem;
  font-weight: 750;
  color: #4ade80;
  font-variant-numeric: tabular-nums;
}

.physics-spring-formulas__live-label {
  margin: 0.15rem 0 0.35rem;
  font-size: 0.72rem;
  color: #94a3b8;
}

.physics-spring-formulas__live-row {
  margin: 0;
  font-size: 0.74rem;
  line-height: 1.55;
  color: #cbd5e1;
}

.physics-spring-formulas__live-note {
  color: #64748b;
}

.physics-spring-formulas__note {
  margin: 0.35rem 0 0;
  padding-top: 0.45rem;
  border-top: 1px solid rgb(148 163 184 / 14%);
  font-size: 0.72rem;
  line-height: 1.5;
  color: #94a3b8;
}

.physics-spring-demo {
  padding: 0.65rem 0.7rem;
  border-radius: 10px;
  border: 1px solid var(--color-hairline, #e2e8f0);
  background: #f8fafc;
  font-size: 0.8rem;
  line-height: 1.45;
  color: var(--color-body, #334155);
}

.physics-spring-demo p {
  margin: 0 0 0.45rem;
}

.physics-spring-charts__head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.35rem 0.65rem;
  margin-bottom: 0.35rem;
  flex: 0 0 auto;
}

.physics-spring-charts__title {
  margin: 0;
  font-size: 0.75rem;
  font-weight: 650;
  color: #94a3b8;
}

.physics-spring-charts__tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin-bottom: 0;
}

.physics-spring-charts__tab {
  min-height: 1.7rem;
  padding: 0 0.65rem;
  border-radius: 999px;
  border: 1px solid #334155;
  background: #1e293b;
  color: #cbd5e1;
  font-size: 0.72rem;
  font-weight: 650;
  cursor: pointer;
}

.physics-spring-charts__tab.is-active {
  background: var(--color-brand, #2260e8);
  border-color: var(--color-brand, #2260e8);
  color: #fff;
}

.physics-spring-charts__canvas {
  width: 100%;
}

.physics-spring-charts__note {
  margin: 0.4rem 0 0;
  font-size: 0.72rem;
  line-height: 1.4;
  color: #94a3b8;
}

.physics-spring-modal {
  position: fixed;
  inset: 0;
  z-index: 80;
  display: grid;
  place-items: center;
  padding: 1rem;
}

.physics-spring-modal__backdrop {
  position: absolute;
  inset: 0;
  border: 0;
  background: rgb(15 23 42 / 45%);
  cursor: pointer;
}

.physics-spring-modal__card {
  position: relative;
  z-index: 1;
  width: min(28rem, 100%);
  padding: 1.1rem 1.15rem 1.2rem;
  border-radius: 14px;
  border: 1px solid var(--color-hairline, #e2e8f0);
  background: #fff;
  box-shadow: 0 16px 40px rgb(15 23 42 / 18%);
  --drag-x: 0px;
  --drag-y: 0px;
  transform: translate(var(--drag-x), var(--drag-y));
  touch-action: none;
}

.physics-spring-modal__card--guide {
  width: min(40rem, 100%);
  max-height: min(88dvh, 52rem);
  display: flex;
  flex-direction: column;
  padding-bottom: 0.85rem;
}

.physics-spring-modal__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.65rem;
  flex: 0 0 auto;
}

.physics-spring-modal__eyebrow {
  margin: 0 0 0.2rem;
  font-size: 0.72rem;
  font-weight: 650;
  letter-spacing: 0.03em;
  color: var(--color-muted, #64748b);
}

.physics-spring-modal__head h2 {
  margin: 0;
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
}

.physics-spring-guide {
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  padding-right: 0.25rem;
  padding-bottom: 0.35rem;
}

.physics-spring-guide__intro {
  margin: 0 0 0.85rem;
  font-size: 0.88rem;
  line-height: 1.55;
  color: var(--color-body, #475569);
}

.physics-spring-guide__section {
  margin: 0 0 1rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--color-hairline, #e2e8f0);
}

.physics-spring-guide__section:first-of-type {
  border-top: 0;
  padding-top: 0;
}

.physics-spring-guide__section h3 {
  margin: 0 0 0.45rem;
  font-size: 0.92rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
}

.physics-spring-guide__section p {
  margin: 0 0 0.55rem;
  font-size: 0.84rem;
  line-height: 1.55;
  color: var(--color-body, #475569);
}

.physics-spring-guide__section ul,
.physics-spring-guide__section ol {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 0.84rem;
  line-height: 1.55;
  color: var(--color-body, #475569);
}

.physics-spring-guide__section li + li {
  margin-top: 0.35rem;
}

.physics-spring-guide__formula {
  display: grid;
  gap: 0.35rem;
  margin: 0.55rem 0;
  padding: 0.65rem 0.75rem;
  border-radius: 10px;
  border: 1px solid color-mix(in oklab, var(--color-brand, #2260e8) 18%, #e2e8f0);
  background: color-mix(in oklab, var(--color-brand, #2260e8) 6%, #fff);
}

.physics-spring-guide__formula .physics-formula-bar {
  margin: 0;
  font-size: 1.05rem;
}

.physics-spring-guide__formula p {
  margin: 0;
  font-size: 0.8rem;
  line-height: 1.45;
  color: var(--color-body, #475569);
}

.physics-guide-tabs {
  display: flex;
  gap: 0.35rem;
  flex-shrink: 0;
  margin: 0 0 0.75rem;
  padding: 0.2rem;
  border-radius: 10px;
  background: color-mix(in oklab, var(--color-ink, #0f172a) 4%, #f1f5f9);
}

.physics-guide-tabs__btn {
  flex: 1;
  margin: 0;
  padding: 0.45rem 0.7rem;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--color-body, #64748b);
  font-size: 0.82rem;
  font-weight: 650;
  cursor: pointer;
}

.physics-guide-tabs__btn:hover {
  color: var(--color-ink, #0f172a);
}

.physics-guide-tabs__btn.is-active {
  background: #fff;
  color: var(--color-ink, #0f172a);
  box-shadow: 0 1px 2px rgb(15 23 42 / 0.08);
}

.physics-guide-formula-pane {
  display: grid;
  gap: 0.85rem;
}

.physics-guide-formula-pane__card {
  margin: 0;
  padding: 0.85rem 0.95rem;
  border-radius: 12px;
  border: 1px solid var(--color-hairline, #e2e8f0);
  background: #fff;
}

.physics-guide-formula-pane__card.is-live {
  border-color: color-mix(in oklab, #f59e0b 28%, #e2e8f0);
  background: color-mix(in oklab, #f59e0b 7%, #fff);
}

.physics-guide-formula-pane__card h3 {
  margin: 0 0 0.55rem;
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
}

.physics-guide-formula-pane__eq {
  margin: 0 0 0.55rem;
  font-size: 1.25rem;
}

.physics-guide-formula-pane__card p,
.physics-guide-formula-pane__hint {
  margin: 0;
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--color-body, #475569);
}

.physics-guide-formula-pane__hint {
  margin-top: 0.65rem;
}

.physics-guide-formula-pane__live {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.55rem;
  margin: 0;
}

.physics-guide-formula-pane__live div {
  padding: 0.45rem 0.5rem;
  border-radius: 8px;
  background: rgb(255 255 255 / 0.75);
}

.physics-guide-formula-pane__live dt {
  margin: 0 0 0.15rem;
  font-size: 0.72rem;
  color: var(--color-body, #64748b);
}

.physics-guide-formula-pane__live dd {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--color-ink, #0f172a);
  font-variant-numeric: tabular-nums;
}

.physics-guide-formula-pane__live dd.is-ok {
  color: #15803d;
}

.physics-guide-formula-pane__card ul {
  margin: 0;
  padding-left: 1.1rem;
  font-size: 0.82rem;
  line-height: 1.55;
  color: var(--color-body, #475569);
}

.physics-guide-formula-pane__card li + li {
  margin-top: 0.35rem;
}

@media (max-width: 520px) {
  .physics-guide-formula-pane__live {
    grid-template-columns: 1fr;
  }
}

/* —— Reflection lab guide (redesigned) —— */
.physics-reflect-guide {
  width: min(44rem, 100%) !important;
  max-height: min(90dvh, 56rem);
  padding: 0 !important;
  overflow: hidden;
  background:
    radial-gradient(90% 60% at 100% 0%, #fff7ed 0%, transparent 55%),
    #fff;
}

.physics-reflect-guide__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  flex: 0 0 auto;
  padding: 1.05rem 1.15rem 0.75rem;
  cursor: grab;
}

.physics-reflect-guide__eyebrow {
  margin: 0 0 0.2rem;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: #b45309;
}

.physics-reflect-guide__head h2 {
  margin: 0;
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: #0f172a;
}

.physics-reflect-guide__sub {
  margin: 0.3rem 0 0;
  font-size: 0.8rem;
  line-height: 1.45;
  color: #64748b;
}

.physics-reflect-guide__close {
  flex: 0 0 auto;
  width: 2rem;
  height: 2rem;
  margin: 0;
  border: 1px solid #e2e8f0;
  border-radius: 999px;
  background: #fff;
  color: #64748b;
  font-size: 1.25rem;
  line-height: 1;
  cursor: pointer;
}

.physics-reflect-guide__close:hover {
  color: #0f172a;
  border-color: #cbd5e1;
}

.physics-reflect-guide__toc {
  display: flex;
  flex-wrap: nowrap;
  gap: 0.35rem;
  flex: 0 0 auto;
  padding: 0 1.15rem 0.75rem;
  overflow-x: auto;
  scrollbar-width: thin;
}

.physics-reflect-guide__toc button {
  flex: 0 0 auto;
  margin: 0;
  padding: 0.32rem 0.65rem;
  border: 1px solid #e2e8f0;
  border-radius: 999px;
  background: #f8fafc;
  color: #475569;
  font-size: 0.74rem;
  font-weight: 650;
  cursor: pointer;
  white-space: nowrap;
}

.physics-reflect-guide__toc button:hover {
  border-color: #f59e0b;
  color: #92400e;
  background: #fffbeb;
}

.physics-reflect-guide__body {
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  padding: 0 1.15rem 1.2rem;
  scroll-behavior: smooth;
}

.physics-reflect-guide__formula {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 0.75rem;
  margin: 0 0 1rem;
  padding: 0.9rem 1rem;
  border-radius: 14px;
  border: 1px solid color-mix(in oklab, #f59e0b 28%, #e2e8f0);
  background: linear-gradient(135deg, #fffbeb 0%, #fff 60%);
}

.physics-reflect-guide__formula-label {
  margin: 0 0 0.25rem;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #b45309;
}

.physics-reflect-guide__eq {
  margin: 0 0 0.4rem;
  font-size: 1.45rem;
}

.physics-reflect-guide__formula-main p {
  margin: 0;
  font-size: 0.8rem;
  line-height: 1.45;
  color: #64748b;
}

.physics-reflect-guide__live {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.4rem;
  margin: 0;
  align-content: center;
}

.physics-reflect-guide__live div {
  padding: 0.45rem 0.4rem;
  border-radius: 10px;
  background: rgb(255 255 255 / 0.85);
  border: 1px solid #fde68a;
  text-align: center;
}

.physics-reflect-guide__live dt {
  margin: 0;
  font-size: 0.68rem;
  color: #92400e;
}

.physics-reflect-guide__live dd {
  margin: 0.1rem 0 0;
  font-size: 1.1rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: #0f172a;
}

.physics-reflect-guide__live dd.is-ok {
  color: #15803d;
}

.physics-reflect-guide__map {
  margin: 0 0 1rem;
}

.physics-reflect-guide__map > h3 {
  margin: 0 0 0.55rem;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #64748b;
}

.physics-reflect-guide__branches {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.55rem;
}

.physics-reflect-guide__branch {
  margin: 0;
  padding: 0.65rem 0.7rem;
  border-radius: 12px;
  border: 1px solid #e2e8f0;
  background: #fff;
}

.physics-reflect-guide__branch.is-orange {
  border-top: 3px solid #f59e0b;
}
.physics-reflect-guide__branch.is-purple {
  border-top: 3px solid #a855f7;
}
.physics-reflect-guide__branch.is-teal {
  border-top: 3px solid #14b8a6;
}
.physics-reflect-guide__branch.is-blue {
  border-top: 3px solid #3b82f6;
}
.physics-reflect-guide__branch.is-pink {
  border-top: 3px solid #ec4899;
}
.physics-reflect-guide__branch.is-amber {
  border-top: 3px solid #d97706;
}

.physics-reflect-guide__branch > h4 {
  margin: 0 0 0.4rem;
  font-size: 0.84rem;
  font-weight: 750;
  color: #0f172a;
}

.physics-reflect-guide__branch > ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.physics-reflect-guide__branch > ul > li {
  margin: 0 0 0.4rem;
}

.physics-reflect-guide__branch > ul > li:last-child {
  margin-bottom: 0;
}

.physics-reflect-guide__branch strong {
  display: block;
  margin-bottom: 0.15rem;
  font-size: 0.76rem;
  font-weight: 700;
  color: #334155;
}

.physics-reflect-guide__branch ul ul {
  margin: 0;
  padding-left: 0.9rem;
  font-size: 0.74rem;
  line-height: 1.4;
  color: #64748b;
}

.physics-reflect-guide__intro {
  margin: 0 0 1rem;
  padding: 0.7rem 0.8rem;
  border-radius: 10px;
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  font-size: 0.82rem;
  line-height: 1.55;
  color: #475569;
}

.physics-reflect-guide__section {
  margin: 0 0 1.1rem;
  padding-top: 0.85rem;
  border-top: 1px solid #e2e8f0;
  scroll-margin-top: 0.5rem;
}

.physics-reflect-guide__section-head {
  display: flex;
  align-items: baseline;
  gap: 0.55rem;
  margin-bottom: 0.55rem;
}

.physics-reflect-guide__num {
  flex: 0 0 auto;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  color: #f59e0b;
}

.physics-reflect-guide__section h3 {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 750;
  color: #0f172a;
}

.physics-reflect-guide__section p {
  margin: 0 0 0.55rem;
  font-size: 0.84rem;
  line-height: 1.55;
  color: #475569;
}

.physics-reflect-guide__section ul,
.physics-reflect-guide__section ol {
  margin: 0 0 0.55rem;
  padding-left: 1.15rem;
  font-size: 0.84rem;
  line-height: 1.55;
  color: #475569;
}

.physics-reflect-guide__section li + li {
  margin-top: 0.3rem;
}

.physics-reflect-guide__inline-formula {
  display: grid;
  gap: 0.35rem;
  margin: 0.55rem 0;
  padding: 0.65rem 0.75rem;
  border-radius: 10px;
  border: 1px solid color-mix(in oklab, #f59e0b 20%, #e2e8f0);
  background: #fffbeb;
}

.physics-reflect-guide__inline-formula p {
  margin: 0;
  font-size: 0.8rem;
}

@media (max-width: 640px) {
  .physics-reflect-guide__formula {
    grid-template-columns: 1fr;
  }

  .physics-reflect-guide__branches {
    grid-template-columns: 1fr;
  }
}

/* Step demo — floating non-modal card (all spring benches; no backdrop) */
.physics-bench--spring .physics-reflect-demo {
  left: auto;
  right: 0.85rem;
  bottom: 0.85rem;
  transform: translate(var(--drag-x), var(--drag-y));
  width: min(22rem, calc(100% - 1.5rem));
  max-height: min(42%, 18rem);
  display: flex;
  flex-direction: column;
  gap: 0;
  overflow: hidden;
  padding: 0.8rem 0.85rem 0.7rem;
  z-index: 35;
  pointer-events: auto;
}

.physics-reflect-demo__heading {
  min-width: 0;
  flex: 1 1 auto;
}

.physics-reflect-demo__step {
  margin: 0;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #94a3b8;
}

.physics-reflect-demo__exit {
  flex: 0 0 auto;
  font-size: 0.72rem !important;
  padding: 0.22rem 0.55rem !important;
  white-space: nowrap;
}

.physics-bench--spring .physics-reflect-demo .physics-spring-demo-card__body {
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  margin: 0 0 0.7rem;
}

.physics-bench--spring .physics-reflect-demo .physics-spring-demo-card__actions {
  flex: 0 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 0.4rem;
}

.physics-bench--spring .physics-reflect-demo .physics-spring-demo-card__actions .btn-secondary,
.physics-bench--spring .physics-reflect-demo .physics-spring-demo-card__actions .btn-brand {
  font-size: 0.76rem;
  padding: 0.35rem 0.65rem;
}

.physics-bench--spring
  .physics-reflect-demo
  .physics-spring-demo-card__actions
  .btn-secondary:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

@media (max-width: 720px) {
  .physics-bench--spring .physics-reflect-demo {
    left: 50%;
    right: auto;
    transform: translate(calc(-50% + var(--drag-x)), var(--drag-y));
    width: min(24rem, calc(100% - 1.25rem));
  }
}

.physics-spring-modal__card ol {
  margin: 0;
  padding-left: 1.2rem;
  color: var(--color-body, #334155);
  font-size: 0.88rem;
  line-height: 1.55;
}

.physics-spring-modal__card li + li {
  margin-top: 0.35rem;
}


/* Convex lens lab ? params sidebar + full stage + bottom meter strip */
.physics-bench--lens.physics-bench--spring {
  grid-template-columns: minmax(18.5rem, 21.5rem) minmax(0, 1fr);
}

.physics-bench--lens.physics-bench--spring .physics-bench__main {
  grid-template-rows: minmax(0, 1fr) auto;
  gap: 0;
}

.physics-bench--lens.physics-bench--spring .physics-bench__stage-slot {
  grid-row: 1;
  padding: var(--demo-glow-room) var(--demo-glow-room) 0.3rem;
}

.physics-bench--lens.physics-bench--spring .physics-bench__stage {
  position: relative;
  min-height: 0;
}

.physics-bench--lens.physics-bench--spring .physics-bench__stage .physics-stage-2d {
  min-height: 280px;
}

.physics-lens-views {
  margin: 0;
  flex-shrink: 0;
}

.physics-lens-canvas3d {
  position: relative;
  flex: 1;
  min-height: 280px;
  height: 100%;
  width: 100%;
}

.physics-lens-canvas3d canvas {
  display: block;
  width: 100% !important;
  height: 100% !important;
}

.physics-lens-3d-hint {
  position: absolute;
  left: 0.65rem;
  bottom: 0.55rem;
  z-index: 2;
  margin: 0;
  padding: 0.28rem 0.55rem;
  border-radius: 8px;
  font-size: 0.72rem;
  color: #cbd5e1;
  background: rgb(15 20 25 / 0.72);
  pointer-events: none;
  white-space: nowrap;
  max-width: min(22rem, calc(100% - 1.5rem));
}

.physics-lens-3d-tag {
  display: inline-block;
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: #fde68a;
  text-shadow: 0 1px 3px rgb(0 0 0 / 0.75);
  white-space: nowrap;
  padding: 0.12rem 0.35rem;
  border-radius: 5px;
  background: rgb(15 20 25 / 0.55);
}

.physics-lens-3d-tag--sm {
  font-size: 0.78rem;
  padding: 0.08rem 0.28rem;
  color: #fdba74;
}

.physics-lens-3d-cue {
  display: inline-block;
  padding: 0.2rem 0.45rem;
  border-radius: 6px;
  font-size: 0.7rem;
  font-weight: 650;
  color: #fecaca;
  background: rgb(127 29 29 / 0.75);
  white-space: nowrap;
}

.physics-bench--lens .physics-lens-hint {
  max-width: min(22rem, calc(100% - 12rem));
  pointer-events: none;
}

/* Magnified receiving-screen preview ? top-right (clown lives here) */
.physics-lens-screen-view {
  position: absolute;
  top: 2.2rem;
  right: 0.65rem;
  z-index: 4;
  width: min(14.5rem, 48vw);
  padding: 0.55rem 0.6rem 0.6rem;
  border: 1px solid rgb(226 232 240 / 0.2);
  border-radius: 14px;
  background: rgb(15 20 25 / 0.92);
  color: #e2e8f0;
  backdrop-filter: blur(10px);
  box-shadow: 0 12px 36px rgb(0 0 0 / 0.45);
  pointer-events: none;
}

.physics-lens-screen-view__head {
  margin-bottom: 0.35rem;
}

.physics-lens-screen-view__eyebrow {
  margin: 0;
  font-size: 0.68rem;
  font-weight: 750;
  letter-spacing: 0.04em;
  color: #e2e8f0;
}

.physics-lens-screen-view__bezel {
  position: relative;
  padding: 5px;
  border-radius: 8px;
  background: linear-gradient(160deg, #4b5563 0%, #1f2937 55%, #111827 100%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 0.18),
    0 2px 8px rgb(0 0 0 / 0.35);
}

.physics-lens-screen-view__bezel.is-live {
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 0.18),
    0 0 0 1px rgb(251 191 36 / 0.28),
    0 2px 10px rgb(0 0 0 / 0.4);
}

.physics-lens-screen-view__bezel.is-blur {
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 0.12),
    0 0 0 1px rgb(148 163 184 / 0.25),
    0 2px 10px rgb(0 0 0 / 0.4);
}

.physics-lens-screen-view__bezel.is-virtual,
.physics-lens-screen-view__bezel.is-empty {
  background: linear-gradient(160deg, #334155 0%, #0f172a 100%);
}

.physics-lens-screen-view__screw {
  position: absolute;
  top: 7px;
  left: 7px;
  z-index: 2;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: radial-gradient(circle at 35% 35%, #e5e7eb, #6b7280 70%);
  box-shadow: 0 0 0 1px #374151;
}

.physics-lens-screen-view__screw.is-br {
  top: auto;
  left: auto;
  right: 7px;
  bottom: 7px;
}

.physics-lens-screen-view__canvas {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 4px;
  vertical-align: top;
}

.physics-lens-screen-view__note {
  position: absolute;
  left: 0.45rem;
  right: 0.45rem;
  bottom: 0.55rem;
  z-index: 3;
  margin: 0;
  padding: 0.2rem 0.3rem;
  border-radius: 4px;
  background: rgb(15 23 42 / 0.55);
  font-size: 0.64rem;
  font-weight: 650;
  line-height: 1.3;
  text-align: center;
  color: #e2e8f0;
}

.physics-lens-screen-view__bezel.is-live .physics-lens-screen-view__note {
  color: #334155;
  background: rgb(248 250 252 / 0.72);
}

.physics-lens-screen-view__meta {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  margin-top: 0.4rem;
  font-size: 0.7rem;
  line-height: 1.3;
  color: #cbd5e1;
}

.physics-lens-screen-view__meta em {
  font-style: normal;
  font-weight: 650;
  color: #fbbf24;
}

.physics-lens-screen-view__m {
  font-variant-numeric: tabular-nums;
  color: #94a3b8;
}

/* Share spring bench shell; only experiment-specific bits below */
.physics-bench--lens.physics-bench--spring .physics-bench__params-scroll {
  flex: 1 1 auto;
}

.physics-bench--lens .physics-lens-layer-row--marks {
  margin-top: 0.45rem;
  padding-top: 0.45rem;
  border-top: 1px dashed #e2e8f0;
}

/* Lens: two actions span the full bar (left + right), equal width */
.physics-bench--lens
  .physics-bench__playback
  .physics-actions.physics-actions--toolbar {
  display: grid;
  grid-template-columns: 1fr 1fr;
  justify-content: stretch;
  align-items: stretch;
  width: 100%;
  margin: 0;
  gap: 0.5rem;
}

.physics-bench--lens
  .physics-bench__playback
  .physics-actions.physics-actions--toolbar
  > button {
  width: 100%;
  min-width: 0;
  justify-content: center;
}

/* Bottom instrument strip (not sidebar readouts) */
.physics-bench--lens .physics-lens-readouts {
  grid-row: 2;
  position: relative;
  display: grid;
  grid-template-columns: minmax(12rem, 1.15fr) minmax(0, 1.6fr);
  gap: 0.65rem 1rem;
  align-items: stretch;
  margin: 0 var(--demo-glow-room) var(--demo-glow-room);
  padding: 0.55rem 0.75rem;
  border: 1px solid var(--color-hairline, #d8dee8);
  border-radius: var(--demo-glow-radius, 12px);
  background: linear-gradient(180deg, #fff 0%, #f8fafc 100%);
  box-shadow: 0 1px 0 rgb(15 23 42 / 3%);
  overflow: visible;
}

.physics-bench--lens .physics-lens-readouts__status {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.15rem;
  min-width: 0;
  padding-right: 0.75rem;
  border-right: 1px solid #e2e8f0;
}

.physics-bench--lens .physics-lens-readouts__eyebrow {
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #94a3b8;
}

.physics-bench--lens .physics-lens-readouts__region {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.25rem 0.45rem;
  margin: 0;
  line-height: 1.3;
}

.physics-bench--lens .physics-lens-readouts__u {
  font-size: 0.78rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: #b45309;
}

.physics-bench--lens .physics-lens-readouts__region strong {
  font-size: 0.88rem;
  font-weight: 750;
  color: #0f172a;
}

.physics-bench--lens .physics-lens-readouts__region em {
  font-size: 0.72rem;
  font-style: normal;
  font-weight: 650;
  color: #92400e;
}

.physics-bench--lens .physics-lens-readouts__detail {
  margin: 0.1rem 0 0;
  font-size: 0.72rem;
  line-height: 1.4;
  color: #64748b;
}

.physics-bench--lens .physics-lens-readouts__grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.4rem;
  margin: 0;
  align-content: center;
}


.physics-bench--lens .physics-lens-readouts__grid > div {
  display: flex;
  flex-direction: column;
  gap: 0.12rem;
  min-width: 0;
  padding: 0.4rem 0.5rem;
  border: 1px solid color-mix(in oklab, var(--color-brand, #2260e8) 12%, #e2e8f0);
  border-radius: 8px;
  background: #fff;
}

.physics-bench--lens .physics-lens-readouts__grid dt {
  margin: 0;
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: #64748b;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.physics-bench--lens .physics-lens-readouts__grid dd {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: var(--color-ink, #0f172a);
  line-height: 1.2;
}

.physics-bench--lens .physics-lens-readouts__sep {
  margin: 0 0.15rem;
  font-weight: 600;
  color: #94a3b8;
}

/* Lens-only: five imaging regions (compact rows inside shared param-group) */
.physics-bench--lens .physics-lens-region-list {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.physics-bench--lens .physics-lens-region-list__item {
  appearance: none;
  display: grid;
  grid-template-columns: 4.75rem minmax(0, 1fr);
  gap: 0.35rem 0.5rem;
  align-items: center;
  width: 100%;
  margin: 0;
  padding: 0.32rem 0.4rem;
  border: 1px solid transparent;
  border-radius: 6px;
  background: transparent;
  color: #334155;
  text-align: left;
  cursor: pointer;
  transition:
    border-color 0.15s ease,
    background 0.15s ease,
    color 0.15s ease;
}

.physics-bench--lens .physics-lens-region-list__item:hover {
  background: #f8fafc;
}

.physics-bench--lens .physics-lens-region-list__item:focus-visible {
  outline: 2px solid color-mix(in oklab, var(--color-brand, #2260e8) 55%, #fff);
  outline-offset: 1px;
}

.physics-bench--lens .physics-lens-region-list__item.is-active {
  border-color: color-mix(in oklab, #f59e0b 45%, #e2e8f0);
  background: color-mix(in oklab, #fbbf24 12%, #fff);
  color: #92400e;
  box-shadow: inset 2px 0 0 #f59e0b;
}

.physics-bench--lens .physics-lens-region-list__u {
  font-size: 0.68rem;
  font-weight: 750;
  font-variant-numeric: tabular-nums;
  color: #64748b;
}

.physics-bench--lens .physics-lens-region-list__item.is-active .physics-lens-region-list__u {
  color: #b45309;
}

.physics-bench--lens .physics-lens-region-list__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.15rem 0.4rem;
  min-width: 0;
}

.physics-bench--lens .physics-lens-region-list__name {
  font-size: 0.74rem;
  font-weight: 650;
  line-height: 1.25;
}

.physics-bench--lens .physics-lens-region-list__app {
  font-size: 0.66rem;
  font-weight: 600;
  color: #64748b;
}

.physics-bench--lens .physics-lens-region-list__item.is-active .physics-lens-region-list__app {
  color: #a16207;
}

/* Keep guided demo above the meter strip */
.physics-bench--lens .physics-lens-demo-card {
  bottom: 5.75rem;
}

.physics-bench--lens .physics-lens-demo-card__count {
  margin-left: auto;
  padding-left: 0.5rem;
  font-size: 0.72rem;
  font-weight: 700;
  color: #94a3b8;
  font-variant-numeric: tabular-nums;
}

.physics-bench--lens .physics-lens-demo-card .physics-spring-demo-card__title {
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
}

.physics-lens-formulas {
  display: grid;
  gap: 0.35rem;
  margin-top: 0.65rem;
}

@media (max-width: 1100px) {
  .physics-bench--lens .physics-lens-readouts {
    grid-template-columns: 1fr;
  }

  .physics-bench--lens .physics-lens-readouts__status {
    padding-right: 0;
    padding-bottom: 0.45rem;
    border-right: 0;
    border-bottom: 1px solid #e2e8f0;
  }

  .physics-bench--lens .physics-lens-readouts__detail {
    display: none;
  }
}

@media (max-width: 900px) {
  .physics-bench--lens.physics-bench--spring {
    grid-template-columns: 1fr;
  }

  .physics-bench--lens.physics-bench--spring .physics-bench__sidebar {
    max-height: min(42vh, 26rem);
  }

  .physics-bench--lens.physics-bench--spring .physics-bench__main {
    grid-template-rows: minmax(240px, 1fr) auto;
    min-height: min(72vh, 38rem);
  }

  .physics-bench--lens.physics-bench--spring .physics-bench__stage .physics-stage-2d {
    min-height: 220px;
  }

  .physics-bench--lens .physics-lens-readouts__grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .physics-bench--lens .physics-lens-region-list__item {
    grid-template-columns: 4.75rem minmax(0, 1fr);
  }

  .physics-bench--lens .physics-lens-demo-card {
    bottom: 7.5rem;
  }

  .physics-lens-screen-view {
    top: 2rem;
    right: 0.4rem;
    width: min(12.5rem, 52vw);
  }
}

/* Plane-mirror lab — same split layout as lens; mirror-specific chrome */
.physics-bench--mirror .physics-mirror-facts {
  list-style: none;
  margin: 0.15rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.35rem;
}

.physics-bench--mirror .physics-mirror-facts__item {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  margin: 0;
  padding: 0.4rem 0.5rem;
  border: 1px solid var(--color-hairline, #e5e7eb);
  border-radius: 8px;
  background: var(--color-surface-soft, #f8f9fa);
  font-size: 0.78rem;
  font-weight: 650;
  color: var(--color-muted, #6b7280);
}

.physics-bench--mirror .physics-mirror-facts__item.is-ok {
  border-color: color-mix(in oklab, #16a34a 28%, var(--color-hairline, #e5e7eb));
  background: color-mix(in oklab, #22c55e 8%, #fff);
  color: #166534;
}

.physics-bench--mirror .physics-mirror-facts__mark {
  display: inline-flex;
  width: 1rem;
  height: 1rem;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  font-size: 0.68rem;
  font-weight: 800;
  background: #e2e8f0;
  color: #64748b;
  flex-shrink: 0;
}

.physics-bench--mirror .physics-mirror-facts__item.is-ok .physics-mirror-facts__mark {
  background: #16a34a;
  color: #fff;
}

.physics-bench--mirror .physics-mirror-hint {
  max-width: min(24rem, calc(100% - 2rem));
}

/* Stage fills main — readouts live in the sidebar under parameters */
.physics-bench--mirror.physics-bench--spring .physics-bench__main {
  grid-template-rows: minmax(0, 1fr);
}

.physics-bench--mirror.physics-bench--spring .physics-bench__stage-slot {
  grid-row: 1;
  padding: 0;
}

.physics-bench--mirror.physics-bench--spring .physics-bench__stage {
  border: none;
  border-radius: 0;
  background: #1e293b;
  box-shadow: none;
}

.physics-bench--mirror.physics-bench--spring .physics-bench__stage .physics-stage-2d {
  border-radius: 0;
}

.physics-bench--mirror .physics-mirror-readouts {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
  margin: 0.15rem 0 0.35rem;
  padding: 0.65rem 0.7rem;
  border: 1px solid var(--color-hairline, #e5e7eb);
  border-radius: 10px;
  background: linear-gradient(180deg, #fff 0%, #f8fafc 100%);
}

.physics-bench--mirror .physics-mirror-readouts__eyebrow {
  display: block;
  font-size: 0.66rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: #94a3b8;
}

.physics-bench--mirror .physics-mirror-readouts__region {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.25rem 0.4rem;
  margin: 0.2rem 0 0;
  line-height: 1.3;
}

.physics-bench--mirror .physics-mirror-readouts__u {
  font-size: 0.78rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: #b45309;
}

.physics-bench--mirror .physics-mirror-readouts__region strong {
  font-size: 0.86rem;
  font-weight: 750;
  color: #0f172a;
}

.physics-bench--mirror .physics-mirror-readouts__region em {
  font-size: 0.72rem;
  font-style: normal;
  font-weight: 650;
  color: #92400e;
}

.physics-bench--mirror .physics-mirror-readouts__detail {
  margin: 0.2rem 0 0;
  font-size: 0.72rem;
  line-height: 1.4;
  color: #64748b;
}

.physics-bench--mirror .physics-mirror-readouts__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.35rem;
  margin: 0;
}

.physics-bench--mirror .physics-mirror-readouts__grid > div {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  min-width: 0;
  padding: 0.38rem 0.45rem;
  border: 1px solid color-mix(in oklab, var(--color-brand, #2260e8) 12%, #e2e8f0);
  border-radius: 8px;
  background: #fff;
}

.physics-bench--mirror .physics-mirror-readouts__grid dt {
  margin: 0;
  font-size: 0.66rem;
  font-weight: 650;
  color: #94a3b8;
}

.physics-bench--mirror .physics-mirror-readouts__grid dd {
  margin: 0;
  font-size: 0.88rem;
  font-weight: 750;
  font-variant-numeric: tabular-nums;
  color: #0f172a;
}

.physics-bench--mirror .physics-reflect-twin__angles {
  grid-template-columns: 1fr 1fr;
}

.physics-bench--mirror .physics-reflect-twin__angles > div {
  text-align: center;
}

.physics-bench--mirror .physics-reflect-twin__angles > div.is-i {
  border-color: color-mix(in oklab, #f59e0b 35%, #e2e8f0);
  background: color-mix(in oklab, #f59e0b 10%, #fff);
}

.physics-bench--mirror .physics-reflect-twin__angles > div.is-r {
  border-color: color-mix(in oklab, #22d3ee 35%, #e2e8f0);
  background: color-mix(in oklab, #22d3ee 10%, #fff);
}

.physics-bench--mirror .physics-reflect-twin__angles dd {
  font-size: 1.35rem;
  font-weight: 800;
}

.physics-bench--mirror .physics-reflect-twin .physics-mirror-readouts__region strong.is-ok {
  color: #15803d;
}

.physics-mirror-facts--compact {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.3rem;
  margin: 0.55rem 0 0;
  padding: 0;
  list-style: none;
}

.physics-mirror-facts--compact .physics-mirror-facts__item {
  margin: 0;
  padding: 0.28rem 0.4rem;
  border-radius: 8px;
  background: rgb(255 255 255 / 0.7);
  font-size: 0.72rem;
}

.physics-mirror-verify-btn {
  margin: 0;
  padding: 0.22rem 0.55rem;
  border-radius: 999px;
  border: 1px solid #e2e8f0;
  background: #f8fafc;
  font-size: 0.7rem;
  font-weight: 650;
  color: #64748b;
  cursor: pointer;
}

.physics-mirror-verify-btn.is-on {
  border-color: color-mix(in oklab, #f59e0b 40%, #e2e8f0);
  background: #fffbeb;
  color: #92400e;
}

/* —— Light reflection: redesigned left control rail —— */
.physics-reflect-side {
  display: flex;
  flex-direction: column;
  min-height: 0;
}

.physics-reflect-side .physics-bench__params-scroll {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  padding: 0.45rem calc(0.7rem + var(--demo-glow-room, 0px) * 0.35) 0.4rem;
  padding-bottom: 0.45rem;
}

.physics-reflect-side__head {
  margin: 0;
  padding: 0 0.05rem 0.1rem;
}

.physics-reflect-side__kicker {
  margin: 0 0 0.08rem;
  font-size: 0.62rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: none;
  color: #94a3b8;
}

.physics-reflect-side__title {
  margin: 0 0 0.18rem;
  font-size: 0.92rem;
  font-weight: 750;
  line-height: 1.3;
  color: #0f172a;
}

.physics-reflect-side__lead {
  margin: 0;
  font-size: 0.72rem;
  line-height: 1.35;
  color: #64748b;
}

.physics-reflect-side__card,
.physics-reflect-side__result,
.physics-reflect-side__layers {
  margin: 0;
  padding: 0.48rem 0.58rem;
  border-radius: 9px;
  border: 1px solid #e2e8f0;
  background: #fff;
}

.physics-reflect-side__card-top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.28rem;
}

.physics-reflect-side__card-top h4,
.physics-reflect-side__layers h4 {
  margin: 0;
  font-size: 0.72rem;
  font-weight: 700;
  color: #334155;
}

.physics-reflect-side__angle {
  font-size: 1.45rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  line-height: 1;
  color: #1d4ed8;
}

.physics-reflect-side__angle small {
  font-size: 0.72em;
  font-weight: 700;
  margin-left: 0.05rem;
}

.physics-reflect-side__slider {
  display: block;
  width: 100%;
  margin: 0;
  accent-color: #2563eb;
}

.physics-reflect-side__range-labels {
  display: flex;
  justify-content: space-between;
  margin-top: 0.25rem;
  font-size: 0.68rem;
  color: #94a3b8;
}

.physics-reflect-side__result {
  background: linear-gradient(165deg, #fffbeb 0%, #fff 55%);
  border-color: color-mix(in oklab, #f59e0b 22%, #e2e8f0);
}

.physics-reflect-side__verdict {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.25rem 0.45rem;
  margin-bottom: 0.35rem;
}

.physics-reflect-side__eq {
  font-size: 0.86rem;
  font-weight: 800;
  color: #b45309;
}

.physics-reflect-side__verdict strong {
  font-size: 0.78rem;
  font-weight: 700;
  color: #64748b;
}

.physics-reflect-side__verdict strong.is-ok {
  color: #15803d;
}

.physics-reflect-side__pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.28rem;
  margin: 0;
}

.physics-reflect-side__pair > div {
  padding: 0.28rem 0.4rem;
  border-radius: 7px;
  background: #fff;
  border: 1px solid #e2e8f0;
}

.physics-reflect-side__pair > div.is-i {
  border-color: color-mix(in oklab, #f59e0b 35%, #e2e8f0);
  background: color-mix(in oklab, #f59e0b 8%, #fff);
}

.physics-reflect-side__pair > div.is-r {
  border-color: color-mix(in oklab, #22d3ee 40%, #e2e8f0);
  background: color-mix(in oklab, #22d3ee 10%, #fff);
}

.physics-reflect-side__pair dt {
  margin: 0 0 0.06rem;
  font-size: 0.62rem;
  color: #64748b;
}

.physics-reflect-side__pair dd {
  margin: 0;
  font-size: 0.98rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  color: #0f172a;
}

.physics-reflect-side__note {
  margin: 0.5rem 0 0;
  font-size: 0.72rem;
  line-height: 1.4;
  color: #64748b;
}

.physics-reflect-side__row {
  display: grid;
  grid-template-columns: 2.6rem minmax(0, 1fr) 3.6rem;
  align-items: center;
  column-gap: 0.45rem;
  margin-top: 0.32rem;
  font-size: 0.74rem;
  color: #475569;
}

.physics-reflect-side__row > span:first-child {
  min-width: 0;
  text-align: right;
  font-weight: 700;
  color: #334155;
  font-variant-numeric: tabular-nums;
}

.physics-reflect-side__row > .physics-stepper {
  width: 100%;
  min-width: 0;
}

.physics-reflect-side__row > span:last-child {
  min-width: 0;
  font-size: 0.68rem;
  color: #94a3b8;
  white-space: nowrap;
  text-align: left;
}

.physics-reflect-side__label {
  margin: 0 0 0.35rem;
  font-size: 0.72rem;
  font-weight: 700;
  color: #64748b;
}

.physics-reflect-side__hint {
  margin: 0.28rem 0 0;
  font-size: 0.66rem;
  line-height: 1.35;
  color: #64748b;
}

.physics-reflect-side__card > h4 {
  margin: 0 0 0.28rem;
  font-size: 0.72rem;
  font-weight: 700;
  color: #334155;
}

.physics-reflect-side__layers h4 {
  margin-bottom: 0.32rem;
}

.physics-reflect-side__chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
}

.physics-reflect-side__chip {
  display: inline-flex;
  align-items: center;
  gap: 0;
  margin: 0;
  padding: 0.18rem 0.42rem;
  border-radius: 999px;
  border: 1px solid #e2e8f0;
  background: #f8fafc;
  font-size: 0.68rem;
  font-weight: 650;
  color: #64748b;
  cursor: pointer;
  user-select: none;
}

.physics-reflect-side__chip input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
  pointer-events: none;
}

.physics-reflect-side__chip.is-on {
  border-color: color-mix(in oklab, #2563eb 35%, #e2e8f0);
  background: color-mix(in oklab, #2563eb 10%, #fff);
  color: #1e3a8a;
}

.physics-reflect-side__chip:hover {
  border-color: #cbd5e1;
}

.physics-reflect-side .physics-formula-bar,
.physics-reflect-side .katex {
  font-size: 0.85em;
}

.physics-reflect-side button.physics-reflect-side__chip {
  font: inherit;
}

@media (max-width: 900px) {
  .physics-bench--mirror .physics-mirror-facts {
    grid-template-columns: 1fr 1fr;
  }

  .physics-bench--mirror.physics-bench--spring .physics-bench__main {
    grid-template-rows: minmax(240px, 1fr);
  }
}

/* ─── Physics pillar page (module landing) ─────────────────────────── */

.physics-pillar__hero {
  max-width: 72rem;
}

.physics-pillar__hero-row {
  display: grid;
  gap: 1.5rem;
  margin-top: 0.35rem;
}

@media (min-width: 900px) {
  .physics-pillar__hero-row {
    grid-template-columns: minmax(0, 1.4fr) minmax(14rem, 0.7fr);
    align-items: end;
    gap: 2rem;
  }
}

.physics-pillar__stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.5rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.physics-pillar__stats li {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 0.85rem 0.75rem;
  border-radius: 12px;
  border: 1px solid var(--ph-line, #e2e8f0);
  background: #fff;
}

.physics-pillar__stat-value {
  font-family: var(--font-display, inherit);
  font-size: 1.25rem;
  font-weight: 750;
  letter-spacing: -0.02em;
  color: var(--color-brand, #2260e8);
  line-height: 1.15;
}

.physics-pillar__stat-label {
  font-size: 0.75rem;
  font-weight: 650;
  color: var(--ph-muted, #64748b);
}

.physics-pillar__stat-link {
  display: grid;
  place-items: center;
  height: 100%;
  min-height: 3.5rem;
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--color-brand, #2260e8);
  text-decoration: none;
}

.physics-pillar__stat-link:hover {
  text-decoration: underline;
}

.physics-pillar__section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: 0.75rem 1.25rem;
  margin-bottom: 1.35rem;
}

.physics-pillar__eyebrow {
  margin: 0 0 0.35rem;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ph-muted, #64748b);
}

.physics-pillar__h2 {
  margin: 0;
  font-family: var(--font-display, inherit);
  font-size: clamp(1.25rem, 2.2vw, 1.5rem);
  font-weight: 750;
  letter-spacing: -0.02em;
  color: var(--ph-ink, #0f172a);
}

.physics-pillar__h3 {
  margin: 0 0 0.85rem;
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ph-muted, #64748b);
}

.physics-pillar__section-meta {
  margin: 0;
  font-size: 0.85rem;
  font-weight: 650;
  color: var(--ph-muted, #64748b);
}

.physics-pillar__exp-grid {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

@media (max-width: 1100px) {
  .physics-pillar__exp-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .physics-pillar__exp-grid {
    grid-template-columns: 1fr;
  }
}

.physics-pillar-guide {
  padding: 0.5rem 0 3rem;
  background:
    radial-gradient(
      ellipse 50% 70% at 100% 0%,
      rgb(34 96 232 / 0.06),
      transparent 55%
    ),
    #f7f8fb;
  border-top: 1px solid var(--ph-line, #e2e8f0);
}

.physics-pillar-guide__panel {
  display: flex;
  flex-direction: column;
  gap: 1.75rem;
  padding: 1.75rem 1.4rem 1.85rem;
  border: 1px solid var(--ph-line, #e2e8f0);
  border-radius: 18px;
  background: #fff;
  box-shadow: 0 1px 2px rgb(15 23 42 / 0.04);
}

@media (min-width: 768px) {
  .physics-pillar-guide__panel {
    padding: 2.15rem 2.1rem 2.25rem;
    gap: 2rem;
  }
}

.physics-pillar-guide__head {
  max-width: 46rem;
  padding-bottom: 1.35rem;
  border-bottom: 1px solid var(--ph-line, #e2e8f0);
}

.physics-pillar-guide__lead {
  margin: 0.75rem 0 0;
  font-size: 1.02rem;
  line-height: 1.7;
  color: #334155;
}

.physics-pillar-guide__bullets {
  display: grid;
  gap: 0.65rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

@media (min-width: 768px) {
  .physics-pillar-guide__bullets {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.physics-pillar-guide__bullets li {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  padding: 0.95rem 1rem;
  border-radius: 12px;
  border: 1px solid var(--ph-line, #e2e8f0);
  background: #f8fafc;
  color: #334155;
  font-size: 0.95rem;
  line-height: 1.55;
}

.physics-pillar-guide__num {
  flex: 0 0 auto;
  font-family: var(--font-display, inherit);
  font-size: 0.8rem;
  font-weight: 750;
  letter-spacing: 0.04em;
  color: var(--color-brand, #2260e8);
  line-height: 1.5;
}

.physics-pillar-guide__formula-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.physics-pillar-guide__formula-list code {
  display: inline-block;
  padding: 0.55rem 0.85rem;
  border-radius: 10px;
  border: 1px solid color-mix(in oklab, #2260e8 22%, #e2e8f0);
  background: color-mix(in oklab, #2260e8 8%, #fff);
  font-size: 0.92rem;
  color: #0f172a;
}

.physics-pillar-guide__bottom {
  display: grid;
  gap: 1.5rem;
  padding-top: 0.35rem;
  border-top: 1px solid var(--ph-line, #e2e8f0);
}

@media (min-width: 960px) {
  .physics-pillar-guide__bottom {
    grid-template-columns: minmax(0, 1.35fr) minmax(15rem, 0.8fr);
    gap: 2rem;
    align-items: start;
  }
}

.physics-pillar-guide__aside {
  padding: 1.2rem 1.1rem;
  border-radius: 14px;
  border: 1px solid var(--ph-line, #e2e8f0);
  background:
    linear-gradient(165deg, rgb(34 96 232 / 0.07) 0%, transparent 55%),
    #f8fafc;
}

.physics-pillar-guide__links {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.physics-pillar-guide__links a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.8rem 0.9rem;
  border-radius: 10px;
  border: 1px solid var(--ph-line, #e2e8f0);
  background: #fff;
  color: #0f172a;
  font-size: 0.9rem;
  font-weight: 650;
  text-decoration: none;
  transition:
    border-color 0.15s ease,
    color 0.15s ease,
    background 0.15s ease;
}

.physics-pillar-guide__links a:hover {
  border-color: color-mix(in oklab, #2260e8 40%, #e2e8f0);
  color: #2260e8;
  background: color-mix(in oklab, #2260e8 6%, #fff);
}

.physics-pillar-guide__faq .nm-seo__h {
  margin-bottom: 0.9rem;
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ph-muted, #64748b);
}

.physics-pillar-related {
  padding: 0 0 3rem;
  background: #fff;
}

.physics-pillar-related .physics-pillar__h2 {
  margin-bottom: 0.9rem;
}

.physics-pillar-related__list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.45rem;
  margin: 0 0 1.5rem;
  padding: 0;
  list-style: none;
}

.physics-pillar-related__list a {
  display: inline-flex;
  padding: 0.45rem 0.8rem;
  border-radius: 8px;
  border: 1px solid var(--ph-line, #e2e8f0);
  background: #f8fafc;
  color: #0f172a;
  font-size: 0.875rem;
  font-weight: 650;
  text-decoration: none;
}

.physics-pillar-related__list a:hover {
  color: #2260e8;
  border-color: color-mix(in oklab, #2260e8 40%, #e2e8f0);
  background: color-mix(in oklab, #2260e8 7%, #fff);
}