:root {
  --bg: #0a0a0f;
  --bg2: #111118;
  --panel: rgba(17, 17, 24, 0.84);
  --panel-strong: rgba(17, 17, 24, 0.96);
  --fg: #e8e4de;
  --fg-dim: #8a8680;
  --fg-soft: rgba(232, 228, 222, 0.84);
  --accent: #c9a96e;
  --accent2: #6ea5c9;
  --accent3: #c96e8a;
  --border: rgba(255, 255, 255, 0.07);
  --border-strong: rgba(201, 169, 110, 0.2);
  --serif: 'EB Garamond', Georgia, serif;
  --mono: 'JetBrains Mono', monospace;
  --shadow: 0 28px 80px rgba(0, 0, 0, 0.34);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scrollbar-width: thin;
  scrollbar-color: var(--accent) var(--bg);
}

body {
  margin: 0;
  background:
    radial-gradient(circle at top left, rgba(110, 165, 201, 0.08), transparent 34%),
    radial-gradient(circle at 80% 0%, rgba(201, 169, 110, 0.08), transparent 30%),
    var(--bg);
  color: var(--fg);
  font-family: var(--serif);
  line-height: 1.7;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

.ambient {
  position: fixed;
  top: 0;
  bottom: 0;
  width: 34vw;
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
}

.ambient-left {
  left: -10vw;
  background: radial-gradient(circle, rgba(110, 165, 201, 0.12), transparent 62%);
}

.ambient-right {
  right: -8vw;
  background: radial-gradient(circle, rgba(201, 169, 110, 0.12), transparent 60%);
}

.site-nav,
.shell,
.chapter-shell {
  position: relative;
  z-index: 1;
}

.site-nav {
  max-width: 1100px;
  margin: 0 auto;
  padding: 22px 28px 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 18px;
}

.nav-link,
.nav-meta,
.eyebrow,
.section-label,
.card-label,
.route-kicker,
.meta-label,
.chapter-map a,
.concept-label,
.fact-label,
.takeaway-label,
.fold summary,
.lab-readout strong,
.metric-label {
  font-family: var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.nav-link,
.nav-meta {
  font-size: 0.72rem;
  color: var(--fg-dim);
}

.nav-link:hover {
  color: var(--accent);
}

.shell {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 28px;
}

.hero {
  padding: 10vh 28px 7vh;
}

.eyebrow {
  margin: 0 0 18px;
  font-size: 0.72rem;
  color: var(--accent);
}

.hero h1,
.chapter-hero h1 {
  margin: 0;
  font-size: clamp(3rem, 6vw, 5.8rem);
  line-height: 0.96;
  font-weight: 400;
  letter-spacing: -0.03em;
}

.hero h1 {
  max-width: 10ch;
}

.chapter-hero h1 {
  max-width: 14ch;
}

.lede {
  max-width: 760px;
  margin: 24px 0 0;
  font-size: 1.35rem;
  color: var(--fg-soft);
}

.inline-accent,
.primary-link:hover,
.chapter-map a:hover,
.chapter-map a:focus-visible {
  color: var(--accent);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-top: 36px;
}

.primary-link,
.secondary-link,
.action-button,
.preset-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 46px;
  padding: 0 18px;
  border-radius: 999px;
  border: 1px solid var(--border);
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transition: transform 180ms ease, border-color 180ms ease, background 180ms ease, color 180ms ease;
}

.primary-link,
.preset-button.active,
.action-button:hover {
  border-color: rgba(201, 169, 110, 0.34);
  background: rgba(201, 169, 110, 0.08);
  color: var(--accent);
}

.secondary-link,
.action-button,
.preset-button {
  color: var(--fg-dim);
  background: rgba(255, 255, 255, 0.02);
}

.primary-link:hover,
.secondary-link:hover,
.action-button:hover,
.preset-button:hover {
  transform: translateY(-1px);
}

.divider {
  width: calc(100% - 56px);
  max-width: 1100px;
  height: 1px;
  margin: 0 auto;
  background: linear-gradient(to right, transparent, rgba(255, 255, 255, 0.18), transparent);
}

.intro-grid,
.route-grid,
 .guide-grid,
 .resource-grid,
 .path-grid {
  display: grid;
  gap: 24px;
}

.intro-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  padding-top: 64px;
}

.editorial-card,
.route-card,
.chapter-map,
.concept-card,
.fact-card,
.viz-panel,
.lab-readout,
.fold {
  border: 1px solid var(--border);
  border-radius: 22px;
  background: var(--panel);
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
}

.editorial-card,
.route-card {
  padding: 28px;
}

.card-label {
  margin: 0 0 12px;
  font-size: 0.7rem;
  color: var(--accent2);
}

.editorial-card h2,
.route-card h3,
.concept-copy h2,
.fold summary {
  margin: 0 0 10px;
  font-weight: 500;
}

.editorial-card h2,
.route-card h3 {
  font-size: clamp(1.5rem, 2.5vw, 2.1rem);
}

.editorial-card p,
.route-card p,
.concept-copy p,
.fact-card p,
.lab-readout p,
.fold-body p,
.fold-body li {
  margin: 0;
  color: var(--fg-soft);
  font-size: 1.08rem;
}

code {
  font-family: var(--mono);
  font-size: 0.88em;
  padding: 1px 6px;
  border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(255, 255, 255, 0.04);
  color: var(--accent2);
}

.route-section {
  padding-top: 80px;
  padding-bottom: 80px;
}

.section-title {
  margin: 10px 0 28px;
  font-size: clamp(2.2rem, 4vw, 3.8rem);
  line-height: 1.05;
  font-weight: 400;
  max-width: 13ch;
}

.route-card {
  margin: 0;
  min-height: 292px;
  padding: 0;
  overflow: hidden;
}

.route-kicker {
  margin: 0 0 8px;
  font-size: 0.7rem;
  color: var(--accent);
}

.route-card-featured {
  border-color: var(--border-strong);
  grid-column: 1 / -1;
  min-height: 0;
}

.route-grid {
  grid-template-columns: repeat(auto-fit, minmax(292px, 1fr));
  align-items: stretch;
}

.route-link {
  display: grid;
  grid-template-rows: auto 1fr auto;
  gap: 22px;
  min-height: 100%;
  padding: 28px;
}

.route-link > div {
  display: grid;
  align-content: start;
  gap: 10px;
}

.route-card h3 {
  margin-bottom: 0;
}

.card-cta {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin-top: auto;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  opacity: 0.92;
  transition: transform 180ms ease, color 180ms ease, opacity 180ms ease;
}

.card-cta::after {
  content: '->';
  letter-spacing: 0.02em;
}

.route-link:hover .card-cta,
.route-link:focus-visible .card-cta {
  transform: translateX(2px);
  color: #dcc08a;
  opacity: 1;
}

.route-link:hover,
.route-link:focus-visible {
  outline: none;
}

.route-link:hover .route-kicker,
.route-link:focus-visible .route-kicker {
  color: #dcc08a;
}

.route-link:hover h3,
.route-link:focus-visible h3 {
  color: #f0ebe4;
}

.site-footer {
  padding-top: 0;
  padding-bottom: 60px;
  color: var(--fg-dim);
  font-size: 0.98rem;
}

.chapter-shell {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 28px 90px;
}

.chapter-hero {
  padding: 8vh 0 34px;
}

.chapter-map {
  position: sticky;
  top: 22px;
  z-index: 4;
  display: flex;
  gap: 18px;
  padding: 14px 18px;
  margin-bottom: 40px;
  overflow-x: auto;
}

.chapter-map a {
  font-size: 0.72rem;
  color: var(--fg-dim);
  white-space: nowrap;
}

.chapter-guide {
  margin: 0 0 30px;
}

.chapter-guide:empty {
  display: none;
}

.chapter-guide .resource-shelf {
  margin: 0 0 30px;
}

.guide-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.guide-card {
  padding: 18px 20px;
  border-radius: 20px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: rgba(255, 255, 255, 0.016);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.02);
}

.guide-card p {
  margin: 0;
  color: var(--fg-soft);
}

.guide-links,
.path-steps {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.guide-link,
.chapter-chip {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 14px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.08);
  background: rgba(255,255,255,0.02);
  color: var(--fg-soft);
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  transition: transform 180ms ease, border-color 180ms ease, color 180ms ease, background 180ms ease;
}

.guide-link:hover,
.chapter-chip:hover {
  transform: translateY(-1px);
  color: var(--accent);
  border-color: rgba(201, 169, 110, 0.22);
  background: rgba(201, 169, 110, 0.05);
}

.resource-shelf {
  background: rgba(255,255,255,0.018);
}

.resource-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.resource-card {
  display: grid;
  gap: 14px;
  padding: 18px 18px 16px;
  border-radius: 18px;
  border: 1px solid rgba(255,255,255,0.06);
  background:
    linear-gradient(180deg, rgba(255,255,255,0.028), rgba(255,255,255,0.012)),
    rgba(255,255,255,0.012);
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.02);
  transition: transform 180ms ease, border-color 180ms ease, background 180ms ease;
}

.resource-card:hover {
  transform: translateY(-1px);
  border-color: rgba(201,169,110,0.18);
  background:
    linear-gradient(180deg, rgba(201,169,110,0.05), rgba(255,255,255,0.012)),
    rgba(255,255,255,0.012);
}

.resource-card h3 {
  margin: 0;
  font-size: 1.26rem;
  line-height: 1.15;
  font-weight: 400;
}

.resource-meta {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}

.resource-type,
.resource-source,
.path-kicker {
  font-family: var(--mono);
  font-size: 0.66rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.resource-type {
  color: var(--accent);
}

.resource-source {
  color: var(--fg-dim);
}

.resource-cta {
  color: var(--fg-dim);
  font-size: 0.96rem;
}

.path-card {
  display: grid;
  gap: 16px;
  padding: 22px;
  border-radius: 22px;
  border: 1px solid rgba(255,255,255,0.06);
  background: rgba(255,255,255,0.016);
}

.path-card h3 {
  margin: 0;
  font-size: 1.8rem;
  font-weight: 400;
  line-height: 1.05;
}

.path-card p {
  margin: 0;
  color: var(--fg-soft);
}

.concept-stack {
  display: grid;
  gap: 46px;
}

.concept-card {
  padding: 30px;
  overflow: hidden;
}

.concept-header {
  max-width: 760px;
  margin-bottom: 26px;
}

.concept-label {
  margin: 0 0 8px;
  font-size: 0.68rem;
  color: var(--accent2);
}

.concept-copy h2 {
  font-size: clamp(2rem, 3.8vw, 3.2rem);
  line-height: 1.04;
}

.concept-summary {
  font-size: 1.24rem;
  color: var(--fg);
}

.concept-layout {
  display: grid;
  grid-template-columns: minmax(0, 0.88fr) minmax(0, 1.12fr);
  gap: 32px;
  align-items: start;
}

.concept-column {
  display: grid;
  gap: 18px;
  min-width: 0;
}

.fact-grid {
  display: grid;
  gap: 16px;
}

.fact-card {
  padding: 18px 20px;
  background: rgba(255, 255, 255, 0.018);
}

.fact-label {
  margin: 0 0 8px;
  font-size: 0.66rem;
  color: var(--accent);
}

.viz-panel {
  position: relative;
  z-index: 1;
  padding: 24px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.03), rgba(255,255,255,0.015)),
    var(--panel-strong);
  overflow: hidden;
}

.viz-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
}

.viz-toolbar-label {
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--fg-dim);
}

.viz-shell {
  display: grid;
  grid-template-areas:
    'stage'
    'readout'
    'support';
  gap: 20px;
}

.viz-support {
  grid-area: support;
}

.viz-stage {
  grid-area: stage;
  cursor: zoom-in;
}

.viz-stage-root {
  width: 100%;
}

.viz-stage:focus-visible {
  outline: 1px solid rgba(201, 169, 110, 0.5);
  outline-offset: 8px;
  border-radius: 18px;
}

.viz-expand-button {
  appearance: none;
  border: 1px solid rgba(201, 169, 110, 0.22);
  border-radius: 999px;
  background: rgba(201, 169, 110, 0.08);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 10px 14px;
  cursor: pointer;
  transition: transform 180ms ease, background 180ms ease, border-color 180ms ease, color 180ms ease;
}

.viz-panel.is-expanded .viz-expand-button {
  position: sticky;
  top: 0;
  right: 0;
  margin-left: auto;
  z-index: 3;
  background: rgba(17, 17, 26, 0.96);
  border-color: rgba(201, 169, 110, 0.42);
}

.viz-panel:not(.is-expanded) .viz-expand-button {
  display: none;
}

.viz-expand-button:hover,
.viz-expand-button:focus-visible {
  transform: translateY(-1px);
  background: rgba(201, 169, 110, 0.14);
  border-color: rgba(201, 169, 110, 0.38);
  color: #f0d6a5;
  outline: none;
}

.control-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  margin-bottom: 4px;
}

.control-group label {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 8px;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--fg-dim);
  letter-spacing: 0.06em;
}

.control-group input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.preset-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 14px;
}

.viz-canvas {
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 740 / 360;
  min-height: 320px;
  border-radius: 18px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background:
    linear-gradient(180deg, rgba(110, 165, 201, 0.04), rgba(0, 0, 0, 0)),
    #0d0d14;
  display: block;
}

.hybrid-stage {
  display: grid;
  gap: 18px;
  padding: 22px;
  min-height: 380px;
  container-type: inline-size;
  container-name: vizstage;
  border-radius: 18px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background:
    linear-gradient(180deg, rgba(110, 165, 201, 0.04), rgba(0, 0, 0, 0)),
    #0d0d14;
}

.viz-panel[data-viewer-layout='wide'] .hybrid-stage {
  min-height: 420px;
}

.viz-panel[data-viewer-layout='comparison'] .hybrid-stage {
  min-height: 400px;
}

.viz-panel[data-renderer-kind='plot'] .hybrid-stage {
  padding-top: 18px;
}

.hybrid-svg {
  width: 100%;
  height: auto;
  display: block;
}

.hv-header {
  display: grid;
  gap: 5px;
}

.hv-title {
  margin: 0;
  font-size: clamp(1.08rem, 1.35vw, 1.34rem);
  line-height: 1.18;
  color: var(--fg);
  max-width: 30ch;
}

.hv-note {
  margin: 0;
  color: var(--fg-soft);
  font-size: 0.94rem;
  line-height: 1.45;
  max-width: 64ch;
}

.hv-grid {
  display: grid;
  gap: 16px;
}

.hv-grid-entropy,
.hv-grid-bayes,
.hv-grid-neuron,
.hv-grid-forward,
.hv-grid-outputs,
.hv-grid-chain,
.hv-grid-backprop,
.hv-grid-attention,
.hv-grid-positional,
.hv-grid-kv,
.hv-grid-mf,
.hv-grid-two-tower,
.hv-grid-tree,
.hv-grid-retrieval,
.hv-grid-diffusion,
.hv-grid-mdp {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.hv-grid-activations {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}

.hv-grid-entropy {
  grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
}

.hv-grid-bayes {
  grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
}

.viz-panel:not(.is-expanded) .hv-grid-bayes {
  grid-template-columns: 1fr;
}

.hv-grid-transformer,
.hv-grid-optimizer-legend {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.hv-card {
  display: grid;
  align-content: start;
  gap: 12px;
  min-width: 0;
  padding: 18px;
  border-radius: 18px;
  border: 1px solid rgba(255,255,255,0.06);
  background:
    linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.025)),
    rgba(255,255,255,0.02);
  box-shadow:
    inset 0 1px 0 rgba(255,255,255,0.02),
    0 16px 32px rgba(0, 0, 0, 0.12);
}

.hv-card-label,
.hv-inline-label,
.hv-badge,
.hv-bar-label,
.hv-bar-value,
.hv-svg-kicker,
.hv-svg-caption,
.hv-svg-label {
  font-family: var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.hv-card-label,
.hv-inline-label,
.hv-svg-kicker,
.hv-svg-caption {
  margin: 0;
  font-size: 0.7rem;
  color: var(--fg-dim);
}

.hv-grid-layer {
  opacity: 1;
}

.hv-footnote {
  margin: 0;
  color: var(--fg-soft);
  font-size: 0.94rem;
  line-height: 1.45;
}

.hv-big-number {
  margin: 0;
  font-size: clamp(2.2rem, 4vw, 3.5rem);
  line-height: 0.95;
  color: var(--fg);
}

.hv-bar-row {
  display: grid;
  gap: 9px;
  padding: 6px 0;
  cursor: help;
  transition: transform 180ms ease, opacity 180ms ease;
}

.hv-bar-row:hover,
.hv-bar-row:focus-within {
  transform: translateX(2px);
}

.hv-bar-top {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}

.hv-bar-label,
.hv-bar-value {
  font-size: 0.7rem;
  color: var(--fg-dim);
}

.hv-bar-track {
  width: 100%;
  height: 13px;
  border-radius: 999px;
  background: rgba(255,255,255,0.07);
  overflow: hidden;
}

.hv-bar-fill {
  height: 100%;
  border-radius: inherit;
}

.hv-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: fit-content;
  max-width: 100%;
  padding: 7px 12px;
  border-radius: 999px;
  background: rgba(255,255,255,0.05);
  color: var(--fg-soft);
  font-size: 0.66rem;
}

.hv-inspector {
  display: grid;
  gap: 8px;
  padding: 14px 16px;
  border-radius: 16px;
  border: 1px solid rgba(255,255,255,0.06);
  background: rgba(255,255,255,0.025);
}

.hv-inspector-title {
  margin: 0;
  font-size: 1.08rem;
  color: var(--fg);
}

.hv-node-target,
.hv-token-target,
.hv-edge-target {
  cursor: pointer;
}

.hv-node-circle,
.hv-edge-line {
  transition: transform 180ms ease, stroke-width 180ms ease, opacity 180ms ease, filter 180ms ease;
}

.hv-node-target.is-active .hv-node-circle,
.hv-node-target:focus .hv-node-circle,
.hv-node-target:hover .hv-node-circle {
  stroke-width: 2.4;
  filter: drop-shadow(0 0 10px rgba(201, 169, 110, 0.22));
}

.hv-node-target.is-active .hv-region-box,
.hv-node-target:focus .hv-region-box,
.hv-node-target:hover .hv-region-box {
  stroke-width: 2.4;
  filter: drop-shadow(0 0 12px rgba(201, 169, 110, 0.18));
}

.hv-node-target.is-active .hv-node-circle {
  stroke: var(--accent);
}

.hv-node-target.is-active .hv-region-box {
  stroke: var(--accent);
}

.hv-node-target:focus,
.hv-token-target:focus,
.hv-edge-target:focus {
  outline: none;
}

.hv-node-target text,
.hv-edge-target text {
  pointer-events: none;
}

.hv-outcome-block {
  display: grid;
  gap: 10px;
  padding: 14px;
  border-radius: 16px;
  background: rgba(255,255,255,0.03);
}

.hv-bayes-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.hv-bayes-strip {
  display: flex;
  min-height: 88px;
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid rgba(255,255,255,0.06);
  background: rgba(255,255,255,0.02);
}

.hv-bayes-segment {
  appearance: none;
  border: 0;
  min-width: 0;
  padding: 16px 14px;
  display: grid;
  align-content: space-between;
  gap: 10px;
  text-align: left;
  color: var(--fg);
  background: transparent;
  cursor: pointer;
  transition: filter 180ms ease, transform 180ms ease, opacity 180ms ease;
}

.hv-bayes-segment:hover,
.hv-bayes-segment:focus-visible,
.hv-bayes-segment.is-active {
  filter: brightness(1.06);
  transform: translateY(-1px);
  outline: none;
}

.hv-bayes-segment-true {
  background: linear-gradient(180deg, rgba(201,169,110,0.55), rgba(201,169,110,0.32));
}

.hv-bayes-segment-false {
  background: linear-gradient(180deg, rgba(201,110,138,0.40), rgba(201,110,138,0.26));
}

.hv-bayes-segment-label,
.hv-bayes-segment-value {
  display: block;
}

.hv-bayes-segment-label {
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.74);
}

.hv-bayes-segment-value {
  font-size: 1.45rem;
}

.hv-bayes-measures {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.hv-bayes-measure {
  display: grid;
  gap: 8px;
  padding: 14px;
  border-radius: 16px;
  background: rgba(255,255,255,0.025);
  border: 1px solid rgba(255,255,255,0.05);
}

.hv-bayes-measure strong {
  font-size: 1.18rem;
  color: var(--fg);
  font-weight: 500;
}

.hv-legend-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  align-items: center;
}

.hv-legend-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-width: 0;
  padding: 10px 12px;
  border-radius: 999px;
  background: rgba(255,255,255,0.03);
}

.hv-swatch {
  width: 10px;
  height: 10px;
  border-radius: 999px;
  flex: 0 0 auto;
}

.hv-swatch-task {
  background: var(--accent-2, #6ea5c9);
}

.hv-swatch-kl {
  background: var(--accent);
}

.hv-swatch-fp {
  background: var(--accent3);
}

.hv-legend-text {
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--fg-dim);
}

.hv-svg-label {
  font-size: 0.7rem;
  fill: var(--fg-soft);
}

.hv-svg-kicker {
  font-size: 0.62rem;
  fill: var(--fg-dim);
}

.hv-svg-caption {
  font-size: 0.76rem;
  fill: var(--fg-dim);
}

.hv-svg-number {
  font-size: 1.24rem;
  fill: var(--fg);
}

.hv-svg-symbol {
  font-size: 1.65rem;
  fill: var(--fg);
}

.hv-accent {
  fill: var(--accent);
}

body.viz-expanded-open {
  overflow: hidden;
}

body.viz-expanded-open .site-nav,
body.viz-expanded-open .chapter-map {
  opacity: 0;
  pointer-events: none;
}

.viz-lightbox[hidden] {
  display: none !important;
}

.viz-lightbox {
  position: fixed;
  inset: 0;
  z-index: 70;
  display: flex;
  align-items: stretch;
  justify-content: center;
  padding: clamp(12px, 2vw, 28px);
  background: rgba(7, 7, 12, 0.82);
  backdrop-filter: blur(10px);
}

.viz-lightbox__dialog {
  width: min(1480px, 100%);
  max-height: 100%;
  overflow: auto;
  padding: clamp(16px, 2vw, 28px);
  border-radius: 28px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.02)),
    #11111a;
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow: 0 28px 90px rgba(0, 0, 0, 0.5);
}

.viz-lightbox__toolbar {
  position: sticky;
  top: 0;
  z-index: 2;
  margin-bottom: 18px;
  padding-bottom: 12px;
  background: linear-gradient(180deg, rgba(17,17,26,0.98), rgba(17,17,26,0.88));
  backdrop-filter: blur(6px);
}

.viz-lightbox__body {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 20px;
}

.viz-lightbox__stage,
.viz-lightbox__readout,
.viz-lightbox__support {
  width: 100%;
}

.viz-lightbox__stage .hybrid-stage,
.viz-lightbox__stage .viz-canvas {
  min-height: min(66vh, 760px);
}

.viz-lightbox__stage .hybrid-stage {
  padding: 28px;
}

.viz-lightbox__dialog[data-viewer-layout='wide'] .hybrid-stage {
  min-height: min(70vh, 820px);
}

.viz-lightbox__dialog[data-viewer-layout='comparison'] .hybrid-stage {
  min-height: min(66vh, 760px);
}

.viz-lightbox__dialog[data-renderer-kind='plot'] .hybrid-stage {
  padding-top: 18px;
}

.viz-lightbox__support {
  padding-top: 2px;
}

.viz-lightbox__support .control-row {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.viz-lightbox__readout {
  margin-top: 0;
  grid-area: auto;
}

.viz-lightbox .takeaway-line {
  font-size: clamp(1.2rem, 2vw, 1.9rem);
}

.viz-lightbox .metric-row {
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
}

.viz-panel.is-expanded {
  position: fixed;
  inset: 2.5vh 2.5vw;
  z-index: 60;
  width: min(1500px, 95vw);
  max-width: 95vw;
  max-height: 95vh;
  margin: auto;
  overflow: auto;
  padding: 28px;
  background:
    linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.02)),
    #11111a;
  border: 1px solid rgba(255, 255, 255, 0.08);
  box-shadow:
    0 0 0 100vmax rgba(7, 7, 12, 0.82),
    0 28px 90px rgba(0, 0, 0, 0.5);
}

.viz-panel.is-expanded .viz-toolbar {
  margin-bottom: 20px;
  position: sticky;
  top: 0;
  z-index: 3;
  padding-bottom: 12px;
  background: linear-gradient(180deg, rgba(17,17,26,0.98), rgba(17,17,26,0.86));
  backdrop-filter: blur(6px);
}

.viz-panel.is-expanded .viz-canvas {
  min-height: 620px;
}

.viz-panel.is-expanded .viz-shell {
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.viz-panel.is-expanded .hybrid-stage {
  min-height: 680px;
  padding: 28px;
}

.viz-panel.is-expanded[data-viewer-layout='wide'] .hybrid-stage {
  min-height: 720px;
}

.viz-panel.is-expanded[data-viewer-layout='comparison'] .hybrid-stage {
  min-height: 680px;
}

.viz-panel.is-expanded .hv-grid-activations {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.viz-panel.is-expanded .viz-stage {
  cursor: default;
  order: 1;
}

.viz-panel.is-expanded .viz-support {
  position: static;
  order: 3;
  padding: 6px 2px 0;
}

.viz-panel.is-expanded .control-row {
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}

.viz-panel.is-expanded .lab-readout {
  margin-top: 0;
  order: 2;
}

.viz-panel.is-expanded .takeaway-line {
  font-size: clamp(1.25rem, 1.7vw, 1.8rem);
}

.viz-panel.is-expanded .hv-title {
  font-size: clamp(1.3rem, 1.7vw, 1.7rem);
  line-height: 1.14;
  max-width: 26ch;
}

.viz-panel.is-expanded .hv-note,
.viz-panel.is-expanded .hv-footnote {
  font-size: 1rem;
  line-height: 1.55;
}

.viz-panel.is-expanded .hv-card {
  padding: 22px;
}

.viz-panel.is-expanded .hv-card-label,
.viz-panel.is-expanded .hv-inline-label,
.viz-panel.is-expanded .hv-svg-kicker,
.viz-panel.is-expanded .hv-svg-caption,
.viz-panel.is-expanded .hv-svg-label,
.viz-panel.is-expanded .hv-bar-label,
.viz-panel.is-expanded .hv-bar-value {
  font-size: 0.78rem;
}

.viz-panel.is-expanded .hv-svg-number {
  font-size: 1.45rem;
}

@container vizstage (max-width: 1120px) {
  .hv-grid-neuron,
  .hv-grid-outputs,
  .hv-grid-chain,
  .hv-grid-backprop,
  .hv-grid-positional,
  .hv-grid-mf,
  .hv-grid-two-tower,
  .hv-grid-tree,
  .hv-grid-retrieval,
  .hv-grid-diffusion,
  .hv-grid-mdp,
  .hv-grid-transformer,
  .hv-grid-optimizer-legend {
    grid-template-columns: 1fr;
  }

  .hv-grid-activations {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .hv-title,
  .hv-note {
    max-width: none;
  }
}

@container vizstage (max-width: 1380px) {
  .hv-grid-entropy,
  .hv-grid-attention,
  .hv-grid-kv,
  .hv-grid-transformer {
    grid-template-columns: 1fr;
  }
}

@container vizstage (max-width: 820px) {
  .hybrid-stage {
    gap: 14px;
    padding: 18px;
  }

  .hv-grid-bayes,
  .hv-grid-activations {
    grid-template-columns: 1fr;
  }

  .hv-title {
    font-size: clamp(1.02rem, 3.2cqw, 1.24rem);
  }

  .hv-note,
  .hv-footnote {
    font-size: 0.95rem;
    line-height: 1.48;
  }

  .hv-card {
    padding: 16px;
  }
}

.lab-readout {
  grid-area: readout;
  margin-top: 18px;
  padding: 20px 22px;
  background: rgba(255, 255, 255, 0.03);
  overflow: hidden;
}

.takeaway-label {
  display: block;
  margin-bottom: 10px;
  font-size: 0.68rem;
  color: var(--accent);
}

.takeaway-line {
  font-size: clamp(1.4rem, 2.5vw, 2rem);
  line-height: 1.15;
  color: var(--fg);
}

.pretext-line {
  display: block;
}

.metric-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 18px;
}

.metric-card {
  padding: 14px 14px 12px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: rgba(255, 255, 255, 0.018);
}

.metric-label {
  display: block;
  margin-bottom: 8px;
  font-size: 0.64rem;
  color: var(--fg-dim);
}

.metric-value {
  font-size: 1.4rem;
  color: var(--fg);
}

.study-tool-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
  margin-top: 24px;
}

.concept-pager {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin-top: 22px;
}

.concept-pager-link,
.concept-pager-spacer {
  min-height: 92px;
  border-radius: 18px;
}

.concept-pager-link {
  display: grid;
  align-content: start;
  gap: 8px;
  padding: 16px 18px;
  border: 1px solid rgba(255,255,255,0.07);
  background: rgba(255,255,255,0.018);
  transition: transform 180ms ease, border-color 180ms ease, background 180ms ease;
}

.concept-pager-link:hover,
.concept-pager-link:focus-visible {
  transform: translateY(-1px);
  border-color: rgba(201, 169, 110, 0.26);
  background: rgba(255,255,255,0.03);
  outline: none;
}

.concept-pager-link-next {
  text-align: right;
}

.concept-pager-label {
  font-family: var(--mono);
  font-size: 0.68rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fg-dim);
}

.concept-pager-title {
  color: var(--fg);
  font-size: 1rem;
}

.study-tool {
  background: rgba(255, 255, 255, 0.02);
}

.study-tool[open] {
  background: rgba(255, 255, 255, 0.024);
  border-color: rgba(201, 169, 110, 0.14);
  box-shadow: 0 22px 54px rgba(0, 0, 0, 0.28);
}

.tool-kicker {
  margin: 0 0 10px;
  font-family: var(--mono);
  font-size: 0.66rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
}

.tool-note,
.quiz-prompt,
.quiz-feedback {
  font-size: 1rem;
  color: var(--fg-soft);
}

.formula-card,
.code-card,
.quiz-card {
  display: grid;
  gap: 12px;
}

.formula-line {
  display: grid;
  gap: 10px;
  padding: 18px 20px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: rgba(255, 255, 255, 0.018);
  font-size: 1.22rem;
  color: var(--fg);
}

.formula-card {
  gap: 14px;
}

.study-tool .fold-body {
  padding-top: 6px;
}

.study-tool[open] .fold-body {
  border-top: 1px solid rgba(255,255,255,0.05);
  background:
    linear-gradient(180deg, rgba(201,169,110,0.026), rgba(255,255,255,0.008) 28%, rgba(255,255,255,0.004));
}

.formula-annotations {
  display: grid;
  gap: 10px;
}

.formula-annotation-list {
  display: grid;
  gap: 10px;
}

.formula-annotation {
  display: grid;
  grid-template-columns: minmax(0, 180px) minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  padding: 14px 16px;
  border-radius: 14px;
  border: 1px solid rgba(255, 255, 255, 0.05);
  background: rgba(255, 255, 255, 0.012);
}

.formula-symbol {
  min-width: 0;
  color: var(--fg);
}

.formula-symbol .katex-display {
  margin: 0;
}

.formula-meaning {
  margin: 0;
  font-size: 1rem;
  color: var(--fg-soft);
}

.formula-copy {
  display: grid;
  gap: 8px;
}

.formula-example {
  margin: 0;
  font-size: 0.98rem;
  color: var(--fg-dim);
}

.formula-example strong {
  color: var(--accent);
  font-weight: 500;
}

.geometry-card {
  gap: 16px;
}

.bayes-geometry {
  display: grid;
  gap: 14px;
}

.bayes-geometry-visual {
  padding: 14px;
  border-radius: 18px;
  border: 1px solid rgba(255,255,255,0.06);
  background:
    linear-gradient(180deg, rgba(255,255,255,0.018), rgba(255,255,255,0.008)),
    rgba(255,255,255,0.012);
}

.bayes-measure-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.bayes-measure-card {
  display: grid;
  gap: 8px;
  padding: 14px 16px;
  border-radius: 16px;
  border: 1px solid rgba(255,255,255,0.05);
  background: rgba(255,255,255,0.02);
}

.bayes-measure-card p {
  font-size: 0.98rem;
}

.bayes-square {
  display: flex;
  min-height: 240px;
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.018), rgba(255, 255, 255, 0.008)),
    rgba(255, 255, 255, 0.012);
}

.bayes-column {
  position: relative;
  flex: 0 0 auto;
  min-width: 0;
  min-height: 240px;
}

.bayes-column + .bayes-column {
  border-left: 1px solid rgba(255, 255, 255, 0.05);
}

.bayes-column::after {
  content: '';
  position: absolute;
  inset: auto 0 0;
  height: 1px;
  background: rgba(255, 255, 255, 0.04);
}

.bayes-column-h {
  background: rgba(201, 169, 110, 0.07);
}

.bayes-column-not-h {
  background: rgba(110, 165, 201, 0.05);
}

.bayes-rect {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  min-height: 12px;
}

.bayes-overlap {
  background:
    linear-gradient(180deg, rgba(201, 169, 110, 0.48), rgba(201, 169, 110, 0.18));
  border-bottom: 1px solid rgba(201, 169, 110, 0.28);
}

.bayes-eonly {
  background:
    linear-gradient(180deg, rgba(201, 110, 138, 0.4), rgba(201, 110, 138, 0.16));
  border-bottom: 1px solid rgba(201, 110, 138, 0.22);
}

.bayes-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 18px;
}

.bayes-legend-item {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--fg-soft);
  font-size: 0.98rem;
}

.bayes-chip {
  width: 18px;
  height: 18px;
  border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.bayes-chip-overlap {
  background: rgba(201, 169, 110, 0.42);
}

.bayes-chip-eonly {
  background: rgba(201, 110, 138, 0.34);
}

.bayes-geometry-note {
  margin-top: -2px;
}

.formula-stack {
  display: grid;
  gap: 12px;
}

.math-frac {
  display: inline-grid;
  gap: 6px;
  align-items: center;
}

.math-frac span:first-child {
  padding-bottom: 6px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.16);
}

.code-card pre {
  margin: 0;
  padding: 18px 20px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: linear-gradient(180deg, rgba(255,255,255,0.02), rgba(0,0,0,0)) , #0d0d14;
  box-shadow: inset 0 1px 0 rgba(255,255,255,0.03);
  overflow-x: auto;
}

.code-card code {
  font-family: var(--mono);
  font-size: 0.88rem;
  line-height: 1.7;
  color: rgba(232, 228, 222, 0.92);
  white-space: pre;
}

.tok-keyword {
  color: #d9a0b8;
}

.tok-module {
  color: var(--blue-light);
}

.tok-number {
  color: var(--gold-light);
}

.tok-comment {
  color: rgba(138, 134, 128, 0.92);
  font-style: italic;
}

.katex-display {
  margin: 0;
}

.formula-line .katex {
  color: var(--fg);
  font-size: 1.02em;
}

.quiz-options {
  display: grid;
  gap: 10px;
}

.quiz-option {
  width: 100%;
  text-align: left;
  justify-content: flex-start;
  min-height: 0;
  padding: 14px 16px;
  border-radius: 16px;
  border: 1px solid rgba(255, 255, 255, 0.07);
  background: rgba(255, 255, 255, 0.018);
  color: var(--fg-soft);
  font-family: var(--serif);
  font-size: 1rem;
  line-height: 1.45;
  cursor: pointer;
  transition: border-color 180ms ease, background 180ms ease, color 180ms ease, transform 180ms ease;
}

.quiz-option:hover {
  transform: translateY(-1px);
  border-color: rgba(201, 169, 110, 0.18);
  background: rgba(201, 169, 110, 0.04);
}

.quiz-option.is-correct {
  border-color: rgba(110, 201, 138, 0.32);
  background: rgba(110, 201, 138, 0.08);
  color: #e7f4e0;
}

.quiz-option.is-wrong {
  border-color: rgba(201, 110, 138, 0.28);
  background: rgba(201, 110, 138, 0.08);
  color: #f3dbe4;
}

.quiz-feedback {
  margin: 0;
  padding-top: 2px;
}

.quiz-feedback.is-correct {
  color: #dcefd4;
}

.quiz-feedback.is-wrong {
  color: #f0d3dd;
}

.fold {
  padding: 0;
  overflow: hidden;
}

.fold summary {
  list-style: none;
  cursor: pointer;
  padding: 18px 20px;
  font-size: 1rem;
  color: var(--fg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.fold summary::-webkit-details-marker {
  display: none;
}

.fold summary::after {
  content: '+';
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.08);
  color: var(--fg-dim);
  font-size: 0.92rem;
  line-height: 1;
  transition: transform 180ms ease, color 180ms ease, border-color 180ms ease, background 180ms ease;
}

.fold[open] summary::after {
  transform: rotate(45deg);
  color: var(--accent);
  border-color: rgba(201,169,110,0.18);
  background: rgba(201,169,110,0.05);
}

.fold-body {
  padding: 0 20px 20px;
}

.fold-body ul {
  margin: 12px 0 0 18px;
}

strong {
  color: var(--fg);
  font-weight: 600;
}

em {
  color: var(--accent);
  font-style: italic;
}

@media (max-width: 960px) {
  .intro-grid,
  .route-grid,
  .concept-layout,
  .metric-row,
  .guide-grid,
  .resource-grid,
  .path-grid {
    grid-template-columns: 1fr;
  }

  .route-card {
    min-height: 0;
  }

  .concept-layout {
    gap: 22px;
  }

  .viz-shell {
    grid-template-areas:
      'stage'
      'readout'
      'support';
  }

  .control-row {
    grid-template-columns: 1fr;
  }

  .viz-panel.is-expanded .viz-shell {
    grid-template-columns: 1fr;
    grid-template-areas:
      'stage'
      'readout'
      'support';
  }

  .viz-panel.is-expanded .viz-support {
    position: static;
  }
}

@media (max-width: 1280px) {
  .viz-lightbox__dialog {
    width: 100%;
  }

  .viz-lightbox__stage .hybrid-stage {
    min-height: auto;
    padding: 22px;
  }

  .viz-panel.is-expanded {
    inset: 2vh 2vw;
    width: auto;
    max-width: none;
    padding: 22px;
  }

  .viz-panel.is-expanded .hybrid-stage {
    min-height: auto;
    padding: 22px;
  }

  .viz-panel.is-expanded .control-row {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .viz-panel.is-expanded .hv-title {
    max-width: none;
  }

  .viz-panel.is-expanded .hv-note,
  .viz-panel.is-expanded .hv-footnote {
    max-width: none;
  }
}

@media (max-width: 640px) {
  .viz-lightbox {
    padding: 8px;
  }

  .viz-lightbox__dialog {
    padding: 14px;
    border-radius: 22px;
  }

  .viz-lightbox__stage .hybrid-stage {
    padding: 18px;
  }

  .viz-lightbox__support .control-row {
    grid-template-columns: 1fr;
  }

  .site-nav,
  .shell,
  .chapter-shell {
    padding-left: 20px;
    padding-right: 20px;
  }

  .hero {
    padding-top: 9vh;
  }

  .hero h1,
  .chapter-hero h1 {
    max-width: none;
  }

  .lede {
    font-size: 1.16rem;
  }

  .concept-card,
  .viz-panel,
  .editorial-card,
  .route-card {
    padding: 20px;
    border-radius: 18px;
  }

  .chapter-map {
    top: 10px;
  }

  .viz-canvas {
    min-height: 240px;
  }

  .viz-toolbar {
    align-items: flex-start;
    flex-direction: column;
  }

  .viz-panel.is-expanded {
    inset: 2.5vh 3vw;
    width: auto;
    max-width: none;
    max-height: 95vh;
    padding: 20px;
  }

  .viz-panel.is-expanded .viz-shell {
    gap: 18px;
  }

  .viz-panel.is-expanded .control-row {
    grid-template-columns: 1fr;
  }

  .viz-panel.is-expanded .viz-canvas {
    min-height: 360px;
  }

  .hybrid-stage {
    min-height: 320px;
    padding: 16px;
  }

  .hv-grid-entropy,
  .hv-grid-bayes,
  .hv-grid-neuron,
  .hv-grid-forward,
  .hv-grid-outputs,
  .hv-grid-chain,
  .hv-grid-backprop,
  .hv-grid-attention,
  .hv-grid-activations,
  .hv-grid-transformer,
  .hv-grid-optimizer-legend {
    grid-template-columns: 1fr;
  }

  .viz-panel:not(.is-expanded) .viz-expand-button {
    display: none;
  }

  .formula-annotation {
    grid-template-columns: 1fr;
  }

  .concept-pager {
    grid-template-columns: 1fr;
  }

  .concept-pager-link-next {
    text-align: left;
  }

  .resource-meta {
    flex-direction: column;
    align-items: start;
  }

  .hv-bayes-measures,
  .bayes-measure-grid {
    grid-template-columns: 1fr;
  }
}

/* ── phone-specific (≤ 480px) ─────────────────────────────────────────── */
@media (max-width: 480px) {

  /* ── desktop hint banner ─── */
  body::before {
    content: 'These visualizations are best experienced on a wider screen.';
    display: block;
    padding: 10px 16px;
    font-family: var(--mono);
    font-size: 0.62rem;
    letter-spacing: 0.08em;
    text-align: center;
    color: var(--fg-dim);
    background: rgba(201, 169, 110, 0.06);
    border-bottom: 1px solid rgba(201, 169, 110, 0.12);
  }

  /* ── overall tightening ─── */
  .site-nav,
  .shell,
  .chapter-shell {
    padding-left: 14px;
    padding-right: 14px;
  }

  .concept-card,
  .viz-panel,
  .editorial-card,
  .route-card {
    padding: 16px;
    border-radius: 16px;
  }

  .concept-copy h2 {
    font-size: 1.6rem;
  }

  .concept-summary {
    font-size: 1.08rem;
  }

  .fact-card {
    padding: 14px 16px;
  }

  .hero {
    padding-top: 7vh;
  }

  .lede {
    font-size: 1.06rem;
  }

  .chapter-map a {
    font-size: 0.72rem;
    padding: 6px 10px;
  }

  /* ── viz stage: show tap-hint & give it a usable size ─── */
  .viz-stage {
    position: relative;
    cursor: pointer;
  }

  .viz-stage::after {
    content: 'Tap to expand';
    position: absolute;
    bottom: 10px;
    right: 10px;
    font-family: var(--mono);
    font-size: 0.6rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--accent);
    background: rgba(10, 10, 15, 0.82);
    border: 1px solid rgba(201, 169, 110, 0.22);
    border-radius: 999px;
    padding: 5px 10px;
    pointer-events: none;
    opacity: 0.85;
  }

  .viz-canvas {
    min-height: 200px;
  }

  .hybrid-stage {
    min-height: 260px;
    padding: 12px;
  }

  /* ── lightbox: truly fullscreen on phones ─── */
  .viz-lightbox {
    padding: 0;
  }

  .viz-lightbox__dialog {
    width: 100%;
    max-height: 100%;
    border-radius: 0;
    padding: 12px;
    border: none;
    overflow-x: hidden;
  }

  .viz-lightbox__stage .hybrid-stage,
  .viz-lightbox__stage .viz-canvas {
    min-height: min(56vh, 420px);
  }

  .viz-lightbox__stage .hybrid-stage {
    padding: 10px;
  }

  /* ── React viz: force all hardcoded grid columns to stack on phone ─── */
  .atelier-react-stage > div > div[style*='grid'] {
    grid-template-columns: 1fr !important;
  }

  /* keep metric cards in 2-col */
  .atelier-react-stage [class*='metric'] {
    grid-template-columns: 1fr 1fr !important;
  }

  .viz-lightbox__toolbar {
    margin-bottom: 10px;
    padding-bottom: 8px;
  }

  .viz-lightbox__close {
    font-size: 0.72rem;
    padding: 8px 14px;
  }

  .viz-lightbox .takeaway-line {
    font-size: 1rem;
  }

  .viz-lightbox .metric-row {
    grid-template-columns: 1fr 1fr;
    gap: 8px;
  }

  /* ── prevent SVG from causing horizontal overflow ─── */
  .hybrid-stage svg {
    max-width: 100%;
    height: auto;
    overflow: hidden;
  }

  /* prevent page-level horizontal scroll from any viz overflow */
  .viz-panel,
  .viz-lightbox__dialog {
    overflow-x: hidden;
  }

  /* ── touch-friendly sliders ─── */
  input[type='range'] {
    height: 36px;
    -webkit-appearance: none;
    appearance: none;
    background: transparent;
    cursor: pointer;
  }

  input[type='range']::-webkit-slider-runnable-track {
    height: 6px;
    border-radius: 3px;
    background: rgba(255, 255, 255, 0.08);
  }

  input[type='range']::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background: var(--accent);
    border: 2px solid rgba(10, 10, 15, 0.9);
    margin-top: -11px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
  }

  .control-group label {
    font-size: 0.82rem;
  }

  .control-row {
    gap: 10px;
  }

  /* ── preset buttons: bigger touch targets ─── */
  .preset-button {
    min-height: 38px;
    padding: 8px 14px;
    font-size: 0.72rem;
  }

  /* ── metric cards ─── */
  .metric-card {
    padding: 10px 12px;
  }

  .metric-value {
    font-size: 1.2rem;
  }

  .metric-label {
    font-size: 0.58rem;
  }

  /* ── readout ─── */
  .lab-readout {
    padding: 12px 14px;
  }

  .takeaway-line {
    font-size: 0.96rem;
  }

  /* ── study tools / folds ─── */
  .fold > summary {
    padding: 12px 14px;
    font-size: 0.82rem;
  }

  .fold-body {
    padding: 12px 14px;
  }

  .formula-card {
    padding: 14px;
  }

  /* ── quiz ─── */
  .quiz-option {
    padding: 12px 14px;
    font-size: 0.92rem;
    min-height: 44px;
  }

  /* ── nav ─── */
  .chapter-map {
    gap: 6px;
    padding: 8px 14px;
  }

  /* ── hybrid viz internal grids: always single-column ─── */
  [class*='hv-grid-'] {
    grid-template-columns: 1fr !important;
  }
}