:root {
  color-scheme: dark;
  --bg: #101110;
  --surface: #171817;
  --surface-raised: #1e1f1e;
  --ink: #f0eee8;
  --muted: #a6a39b;
  --faint: #77766f;
  --line: rgba(240, 238, 232, 0.16);
  --line-strong: rgba(240, 238, 232, 0.34);
  --accent: #e8653d;
  --accent-ink: #15110f;
  --topbar: rgba(16, 17, 16, 0.88);
  --scene-wash: rgba(16, 17, 16, 0.18);
  --sans: "Helvetica Neue", "Arial Nova", Arial, sans-serif;
  --mono: "SFMono-Regular", "Cascadia Code", "Roboto Mono", Consolas, monospace;
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme]) {
    color-scheme: light;
    --bg: #e8e6df;
    --surface: #dedbd2;
    --surface-raised: #f0eee8;
    --ink: #191a18;
    --muted: #5f5e58;
    --faint: #77756d;
    --line: rgba(25, 26, 24, 0.17);
    --line-strong: rgba(25, 26, 24, 0.38);
    --accent: #ae3b1a;
    --accent-ink: #f5f1ea;
    --topbar: rgba(232, 230, 223, 0.9);
    --scene-wash: rgba(232, 230, 223, 0.12);
  }
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #e8e6df;
  --surface: #dedbd2;
  --surface-raised: #f0eee8;
  --ink: #191a18;
  --muted: #5f5e58;
  --faint: #77756d;
  --line: rgba(25, 26, 24, 0.17);
  --line-strong: rgba(25, 26, 24, 0.38);
  --accent: #ae3b1a;
  --accent-ink: #f5f1ea;
  --topbar: rgba(232, 230, 223, 0.9);
  --scene-wash: rgba(232, 230, 223, 0.12);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #101110;
  --surface: #171817;
  --surface-raised: #1e1f1e;
  --ink: #f0eee8;
  --muted: #a6a39b;
  --faint: #77766f;
  --line: rgba(240, 238, 232, 0.16);
  --line-strong: rgba(240, 238, 232, 0.34);
  --accent: #e8653d;
  --accent-ink: #15110f;
  --topbar: rgba(16, 17, 16, 0.88);
  --scene-wash: rgba(16, 17, 16, 0.18);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--bg);
}

body {
  margin: 0;
  overflow-x: hidden;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body::after {
  position: fixed;
  inset: 0;
  z-index: 60;
  pointer-events: none;
  content: "";
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 180 180' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.88' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='.65'/%3E%3C/svg%3E");
}

button,
input,
a {
  font: inherit;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

a {
  color: inherit;
}

button {
  color: inherit;
}

::selection {
  background: var(--accent);
  color: var(--accent-ink);
}

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 90;
  padding: 10px 14px;
  border: 1px solid var(--ink);
  background: var(--bg);
  color: var(--ink);
  font: 600 12px/1 var(--mono);
  text-decoration: none;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.topbar {
  position: fixed;
  inset: 0 0 auto;
  z-index: 20;
  display: grid;
  grid-template-columns: minmax(120px, 1fr) minmax(160px, auto) minmax(280px, 1fr);
  align-items: center;
  min-height: 64px;
  padding: 0 24px;
  border-bottom: 1px solid var(--line);
  background: var(--topbar);
  backdrop-filter: blur(16px) saturate(130%);
  -webkit-backdrop-filter: blur(16px) saturate(130%);
}

.wordmark,
.topbar-note,
.topbar-actions {
  font: 600 11px/1 var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.wordmark {
  width: fit-content;
  padding: 6px 0;
  text-decoration: none;
}

.wordmark::after {
  display: inline-block;
  width: 20px;
  height: 1px;
  margin: 0 0 3px 10px;
  background: var(--accent);
  content: "";
}

.topbar-note {
  margin: 0;
  color: var(--muted);
  text-align: center;
}

.topbar-actions {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: 22px;
}

.topbar-actions a,
.theme-toggle {
  position: relative;
  padding: 8px 0;
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  text-decoration: none;
}

.topbar-actions a::after,
.theme-toggle::after {
  position: absolute;
  right: 0;
  bottom: 2px;
  left: 0;
  height: 1px;
  background: var(--accent);
  content: "";
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 280ms var(--ease);
}

.app-grid {
  display: grid;
  grid-template-columns: minmax(0, 48vw) minmax(0, 52vw);
  align-items: start;
}

.content {
  position: relative;
  z-index: 2;
  grid-column: 1;
  min-width: 0;
  background: var(--bg);
}

.hero,
.chapter {
  scroll-margin-top: 64px;
}

.hero {
  display: flex;
  min-height: 100dvh;
  padding: 96px clamp(24px, 5vw, 78px) 7vh;
  align-items: flex-end;
  border-bottom: 1px solid var(--line);
}

.hero-inner {
  width: min(100%, 700px);
}

.eyebrow {
  margin: 0 0 24px;
  color: var(--accent);
  font: 600 11px/1.2 var(--mono);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  text-wrap: pretty;
}

h1 {
  max-width: 12ch;
  margin: 0;
  font-size: clamp(3.55rem, 6.35vw, 6.4rem);
  font-stretch: condensed;
  font-weight: 500;
  letter-spacing: -0.067em;
  line-height: 0.9;
}

.hero-copy {
  max-width: 37ch;
  margin: 34px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 1.25vw, 1.18rem);
  line-height: 1.55;
}

.primary-action {
  display: inline-flex;
  width: fit-content;
  min-height: 48px;
  margin-top: 34px;
  padding: 0 18px;
  align-items: center;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: var(--accent-ink);
  font: 650 12px/1 var(--mono);
  letter-spacing: 0.04em;
  text-decoration: none;
  white-space: nowrap;
  transition: background 220ms ease, color 220ms ease, transform 180ms ease;
}

.primary-action:active,
.action-button:active,
.topology-option:active,
.material-option:active {
  transform: translateY(1px);
}

.chapter {
  min-height: 100dvh;
  padding: clamp(90px, 10vw, 150px) clamp(24px, 5vw, 78px) clamp(90px, 10vw, 150px);
  border-bottom: 1px solid var(--line);
}

.chapter-heading {
  display: flex;
  max-width: 660px;
  flex-direction: column;
  gap: 24px;
}

.chapter-heading h2 {
  max-width: 11ch;
  margin: 0;
  font-size: clamp(2.65rem, 4.3vw, 4.75rem);
  font-stretch: condensed;
  font-weight: 500;
  letter-spacing: -0.055em;
  line-height: 0.95;
}

.chapter-heading p {
  max-width: 47ch;
  margin: 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.65;
}

.control-stack {
  margin-top: clamp(56px, 8vw, 96px);
  border-top: 1px solid var(--line-strong);
}

.range-control {
  position: relative;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 18px;
  padding: 24px 0 22px;
  border-bottom: 1px solid var(--line);
}

.control-name {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.control-value {
  color: var(--accent);
  font: 500 13px/1.5 var(--mono);
  font-variant-numeric: tabular-nums;
}

.range-control input[type="range"] {
  grid-column: 1 / -1;
  width: 100%;
  height: 18px;
  margin: 0;
  appearance: none;
  background: transparent;
  cursor: ew-resize;
}

.range-control input[type="range"]::-webkit-slider-runnable-track {
  height: 1px;
  background: linear-gradient(to right, var(--accent) 0 var(--range-progress, 50%), var(--line-strong) var(--range-progress, 50%) 100%);
}

.range-control input[type="range"]::-moz-range-track {
  height: 1px;
  background: var(--line-strong);
}

.range-control input[type="range"]::-moz-range-progress {
  height: 1px;
  background: var(--accent);
}

.range-control input[type="range"]::-webkit-slider-thumb {
  width: 14px;
  height: 14px;
  margin-top: -6px;
  appearance: none;
  border: 2px solid var(--bg);
  border-radius: 0;
  background: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.range-control input[type="range"]::-moz-range-thumb {
  width: 12px;
  height: 12px;
  border: 2px solid var(--bg);
  border-radius: 0;
  background: var(--accent);
  box-shadow: 0 0 0 1px var(--accent);
}

.range-ends {
  display: flex;
  grid-column: 1 / -1;
  justify-content: space-between;
  color: var(--faint);
  font: 500 10px/1 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.process-image {
  position: relative;
  width: calc(100% + clamp(24px, 5vw, 78px));
  margin: clamp(70px, 9vw, 120px) 0 0;
  overflow: hidden;
  background: var(--surface);
}

.process-image img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.82) contrast(1.04);
  transition: filter 500ms ease, transform 900ms var(--ease);
}

.process-image-direction {
  height: clamp(280px, 38vw, 540px);
  margin-left: clamp(-34px, -2.4vw, -18px);
  transform: translateX(-2vw);
}

.process-image-direction img {
  object-position: 62% 50%;
}

.process-image-structure {
  height: clamp(300px, 32vw, 500px);
  width: calc(100% + clamp(48px, 8vw, 120px));
  margin-left: clamp(-24px, -3vw, -48px);
  clip-path: polygon(0 9%, 100% 0, 100% 91%, 0 100%);
}

.process-image-delivery {
  height: clamp(310px, 40vw, 560px);
}

.process-image-delivery img {
  object-position: 56% 50%;
}

fieldset {
  min-width: 0;
  margin: 0;
  padding: 0;
  border: 0;
}

legend {
  width: 100%;
  padding: 0 0 16px;
  border-bottom: 1px solid var(--line-strong);
  color: var(--muted);
  font: 600 11px/1 var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.topology-control,
.material-control {
  margin-top: clamp(56px, 8vw, 96px);
}

.topology-options,
.material-options {
  display: grid;
}

.topology-option {
  position: relative;
  display: grid;
  grid-template-columns: minmax(90px, 0.7fr) minmax(150px, 1fr) 86px;
  min-height: 104px;
  padding: 22px 0;
  align-items: center;
  gap: 18px;
  border: 0;
  border-bottom: 1px solid var(--line);
  background: transparent;
  text-align: left;
  cursor: pointer;
  transition: color 240ms ease, padding 320ms var(--ease), background 240ms ease, transform 180ms ease;
}

.topology-name {
  font-size: 1.18rem;
  font-weight: 600;
  letter-spacing: -0.025em;
}

.topology-copy {
  color: var(--muted);
  font-size: 0.86rem;
}

.topology-mark {
  position: relative;
  display: block;
  width: 74px;
  height: 42px;
  justify-self: end;
}

.topology-mark i {
  position: absolute;
  display: block;
  border: 1px solid currentColor;
  transition: transform 500ms var(--ease);
}

.topology-mark-orbit i:first-child {
  inset: 4px 16px;
  border-radius: 50%;
}

.topology-mark-orbit i:last-child {
  inset: 12px 2px;
  border-radius: 50%;
  transform: rotate(-18deg);
}

.topology-mark-span i:first-child {
  top: 8px;
  right: 2px;
  bottom: 8px;
  left: 2px;
  border-width: 1px 0;
  transform: skewY(-12deg);
}

.topology-mark-span i:last-child {
  top: 20px;
  right: 8px;
  left: 8px;
  height: 1px;
  border: 0;
  background: currentColor;
  transform: rotate(20deg);
}

.topology-mark-fold i:first-child {
  inset: 3px 22px 3px 8px;
  transform: skewX(-18deg);
}

.topology-mark-fold i:last-child {
  inset: 10px 6px 9px 30px;
  transform: skewX(18deg);
}

.topology-option.is-selected {
  padding-right: 14px;
  padding-left: 14px;
  background: var(--surface);
  color: var(--accent);
}

.topology-option.is-selected .topology-copy {
  color: var(--ink);
}

.topology-option.is-selected .topology-mark i:last-child {
  transform: rotate(36deg) scale(1.08);
}

.material-options {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border-bottom: 1px solid var(--line);
}

.material-option {
  position: relative;
  display: flex;
  min-height: 142px;
  padding: 22px 18px 20px;
  flex-direction: column;
  justify-content: flex-end;
  border-right: 1px solid var(--line);
  cursor: pointer;
  transition: background 240ms ease, color 240ms ease, transform 180ms ease;
}

.material-option:last-child {
  border-right: 0;
}

.material-option input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}

.material-option span {
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: -0.02em;
}

.material-option small {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.72rem;
  line-height: 1.4;
}

.material-option::before {
  position: absolute;
  top: 22px;
  left: 18px;
  width: 28px;
  height: 28px;
  border: 1px solid var(--line-strong);
  content: "";
}

.material-option:nth-child(1)::before {
  background: linear-gradient(135deg, #4b4d4b, #171817);
}

.material-option:nth-child(2)::before {
  background: linear-gradient(135deg, rgba(232, 230, 223, 0.42), rgba(92, 96, 93, 0.12));
  backdrop-filter: blur(4px);
}

.material-option:nth-child(3)::before {
  background-image: linear-gradient(45deg, transparent 46%, var(--line-strong) 47% 53%, transparent 54%), linear-gradient(-45deg, transparent 46%, var(--line-strong) 47% 53%, transparent 54%);
  background-size: 8px 8px;
}

.material-option.is-selected {
  background: var(--accent);
  color: var(--accent-ink);
}

.material-option.is-selected small {
  color: currentColor;
  opacity: 0.72;
}

.material-option.is-selected::before {
  border-color: currentColor;
}

.energy-control {
  margin-top: 34px;
  border-top: 1px solid var(--line-strong);
}

.interaction-note {
  max-width: 44ch;
  margin: 38px 0 0;
  color: var(--muted);
  font: 500 12px/1.65 var(--mono);
}

.recipe {
  margin-top: clamp(70px, 9vw, 120px);
  border-top: 1px solid var(--line-strong);
}

.recipe-heading {
  display: flex;
  padding: 24px 0;
  justify-content: space-between;
  align-items: baseline;
  gap: 24px;
  border-bottom: 1px solid var(--line);
}

.recipe-heading h3 {
  margin: 0;
  font-size: 1.3rem;
  font-weight: 600;
  letter-spacing: -0.03em;
}

.recipe-heading p {
  margin: 0;
  color: var(--accent);
  font: 500 11px/1.3 var(--mono);
}

.recipe dl {
  margin: 0;
}

.recipe dl > div {
  display: grid;
  grid-template-columns: minmax(100px, 0.36fr) 1fr;
  gap: 20px;
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.recipe dt {
  color: var(--muted);
  font: 600 10px/1.55 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.recipe dd {
  margin: 0;
  font-size: 0.92rem;
}

.delivery-actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  margin-top: 28px;
  border: 1px solid var(--line-strong);
}

.action-button {
  min-height: 52px;
  padding: 0 18px;
  border: 0;
  border-right: 1px solid var(--line-strong);
  background: transparent;
  font: 600 12px/1 var(--mono);
  cursor: pointer;
  white-space: nowrap;
  transition: background 220ms ease, color 220ms ease, transform 180ms ease;
}

.action-button:last-child {
  border-right: 0;
}

.action-button-primary {
  background: var(--accent);
  color: var(--accent-ink);
}

.site-footer {
  display: flex;
  min-height: 190px;
  padding: 42px clamp(24px, 5vw, 78px);
  justify-content: space-between;
  align-items: flex-end;
  gap: 28px;
  color: var(--muted);
  font: 600 10px/1.5 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.site-footer p {
  margin: 0;
}

.site-footer a {
  padding-bottom: 4px;
  border-bottom: 1px solid var(--accent);
  color: var(--ink);
  text-decoration: none;
}

.scene-panel {
  position: sticky;
  top: 0;
  z-index: 1;
  grid-column: 2;
  grid-row: 1;
  height: 100dvh;
  overflow: hidden;
  border-left: 1px solid var(--line);
  background: var(--surface);
  isolation: isolate;
}

.scene-panel::before,
.scene-panel::after {
  position: absolute;
  inset: 0;
  z-index: 2;
  pointer-events: none;
  content: "";
}

.scene-panel::before {
  background: linear-gradient(90deg, var(--scene-wash), transparent 24%), linear-gradient(0deg, rgba(12, 13, 12, 0.26), transparent 28%);
}

.scene-panel::after {
  inset: 64px 0 auto;
  height: 1px;
  background: var(--line);
}

.scene-fallback {
  position: absolute;
  inset: 0;
  z-index: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 64% 50%;
  filter: saturate(0.82) contrast(1.05);
  transition: opacity 900ms var(--ease), filter 900ms var(--ease), transform 1400ms var(--ease);
}

.scene-panel.is-ready .scene-fallback {
  opacity: 0.08;
  filter: saturate(0.3) contrast(1.2);
  transform: scale(1.04);
}

#fieldCanvas {
  position: absolute;
  inset: 0;
  z-index: 1;
  display: block;
  width: 100%;
  height: 100%;
  opacity: 0;
  outline: none;
  touch-action: none;
  cursor: grab;
  transition: opacity 800ms var(--ease);
}

#fieldCanvas:active {
  cursor: grabbing;
}

#fieldCanvas:focus-visible {
  box-shadow: inset 0 0 0 2px var(--accent);
}

.scene-panel.is-ready #fieldCanvas {
  opacity: 1;
}

.scene-loading {
  position: absolute;
  right: clamp(20px, 3vw, 42px);
  bottom: clamp(26px, 4vw, 52px);
  left: clamp(20px, 3vw, 42px);
  z-index: 4;
  display: grid;
  gap: 12px;
  color: var(--ink);
  font: 600 10px/1 var(--mono);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  transition: opacity 300ms ease, visibility 300ms ease;
}

.loading-line {
  position: relative;
  display: block;
  width: 100%;
  height: 1px;
  overflow: hidden;
  background: var(--line-strong);
}

.loading-line::after {
  position: absolute;
  inset: 0;
  background: var(--accent);
  content: "";
  transform: translateX(-100%);
  animation: loading-sweep 1.4s var(--ease) infinite;
}

@keyframes loading-sweep {
  to { transform: translateX(100%); }
}

.scene-panel.is-ready .scene-loading {
  opacity: 0;
  visibility: hidden;
}

.scene-error {
  position: absolute;
  right: 28px;
  bottom: 34px;
  left: 28px;
  z-index: 5;
  display: grid;
  gap: 5px;
  padding-top: 16px;
  border-top: 1px solid var(--line-strong);
  font: 500 11px/1.5 var(--mono);
}

.scene-error strong {
  color: var(--accent);
  font-weight: 600;
}

.scene-error span {
  color: var(--muted);
}

.scene-error[hidden] {
  display: none;
}

.scene-meta {
  position: absolute;
  right: clamp(20px, 3vw, 42px);
  bottom: clamp(24px, 3vw, 38px);
  left: clamp(20px, 3vw, 42px);
  z-index: 3;
  display: flex;
  justify-content: space-between;
  gap: 24px;
  padding-top: 14px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font: 600 10px/1 var(--mono);
  letter-spacing: 0.09em;
  text-transform: uppercase;
  opacity: 0;
  transition: opacity 500ms ease 400ms;
}

.scene-panel.is-ready .scene-meta {
  opacity: 1;
}

.chapter-nav {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 15;
  display: grid;
  width: min(42vw, 540px);
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border: 1px solid var(--line-strong);
  background: var(--topbar);
  backdrop-filter: blur(18px) saturate(130%);
  -webkit-backdrop-filter: blur(18px) saturate(130%);
}

.chapter-nav button {
  min-width: 0;
  min-height: 46px;
  padding: 0 10px;
  overflow: hidden;
  border: 0;
  border-right: 1px solid var(--line);
  background: transparent;
  color: var(--muted);
  font: 600 10px/1 var(--mono);
  text-overflow: ellipsis;
  white-space: nowrap;
  cursor: pointer;
  transition: background 220ms ease, color 220ms ease;
}

.chapter-nav button:last-child {
  border-right: 0;
}

.chapter-nav button.is-active {
  background: var(--accent);
  color: var(--accent-ink);
}

.noscript-note {
  position: fixed;
  right: 24px;
  bottom: 88px;
  z-index: 30;
  max-width: 360px;
  padding: 14px 16px;
  border: 1px solid var(--accent);
  background: var(--bg);
  color: var(--ink);
  font: 500 11px/1.5 var(--mono);
}

@media (hover: hover) {
  .topbar-actions a:hover,
  .theme-toggle:hover {
    color: var(--ink);
  }

  .topbar-actions a:hover::after,
  .theme-toggle:hover::after {
    transform: scaleX(1);
  }

  .primary-action:hover {
    background: transparent;
    color: var(--accent);
  }

  .topology-option:hover:not(.is-selected) {
    padding-right: 10px;
    padding-left: 10px;
    background: var(--surface);
  }

  .material-option:hover:not(.is-selected) {
    background: var(--surface);
  }

  .action-button:hover:not(.action-button-primary) {
    background: var(--surface-raised);
  }

  .action-button-primary:hover {
    background: transparent;
    color: var(--accent);
  }

  .process-image:hover img {
    filter: saturate(1) contrast(1.02);
    transform: scale(1.02);
  }
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
label:has(input:focus-visible) {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
}

@media (max-width: 1060px) and (min-width: 761px) {
  .app-grid {
    grid-template-columns: minmax(0, 52vw) minmax(0, 48vw);
  }

  .topbar-note {
    display: none;
  }

  .topbar {
    grid-template-columns: 1fr auto;
  }

  h1 {
    font-size: clamp(3.35rem, 7.1vw, 5rem);
  }

  .material-options {
    grid-template-columns: 1fr;
  }

  .material-option {
    min-height: 105px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .topology-option {
    grid-template-columns: 0.7fr 1fr;
  }

  .topology-copy {
    display: none;
  }

  .chapter-nav {
    width: calc(48vw - 48px);
  }
}

@media (max-width: 760px) {
  .topbar {
    grid-template-columns: 1fr auto;
    min-height: 58px;
    padding: 0 15px;
  }

  .topbar-note,
  .theme-toggle {
    display: none;
  }

  .topbar-actions {
    gap: 0;
  }

  .app-grid {
    display: flex;
    flex-direction: column;
  }

  .scene-panel {
    position: sticky;
    top: 58px;
    z-index: 6;
    order: 0;
    width: 100%;
    height: 38dvh;
    min-height: 260px;
    max-height: 390px;
    border-bottom: 1px solid var(--line);
    border-left: 0;
  }

  .scene-panel::after {
    display: none;
  }

  .scene-fallback {
    object-position: 67% 48%;
  }

  .scene-meta {
    right: 15px;
    bottom: 15px;
    left: 15px;
    padding-top: 10px;
    font-size: 8px;
  }

  .content {
    z-index: 2;
    order: 1;
    width: 100%;
  }

  .hero {
    min-height: calc(62dvh - 58px);
    padding: 24px 20px 86px;
    scroll-margin-top: calc(38dvh + 58px);
  }

  .eyebrow {
    margin-bottom: 16px;
    font-size: 9px;
  }

  h1 {
    max-width: 10ch;
    font-size: clamp(2.85rem, 13.8vw, 4.2rem);
    line-height: 0.92;
  }

  .hero-copy {
    margin-top: 20px;
    font-size: 0.93rem;
  }

  .primary-action {
    min-height: 44px;
    margin-top: 22px;
  }

  .chapter {
    min-height: 122dvh;
    padding: calc(38dvh + 74px) 20px 94px;
    scroll-margin-top: 58px;
  }

  .chapter-heading {
    gap: 18px;
  }

  .chapter-heading h2 {
    font-size: clamp(2.4rem, 12vw, 3.4rem);
  }

  .chapter-heading p {
    font-size: 0.94rem;
  }

  .control-stack,
  .topology-control,
  .material-control {
    margin-top: 52px;
  }

  .range-control {
    padding: 20px 0;
  }

  .process-image,
  .process-image-direction,
  .process-image-structure,
  .process-image-delivery {
    width: calc(100% + 40px);
    height: 67vw;
    margin-top: 64px;
    margin-left: -20px;
    clip-path: none;
    transform: none;
  }

  .process-image-structure {
    height: 57vw;
  }

  .topology-option {
    grid-template-columns: minmax(76px, 0.6fr) minmax(120px, 1fr) 68px;
    min-height: 94px;
    gap: 10px;
  }

  .topology-mark {
    width: 60px;
  }

  .topology-copy {
    font-size: 0.74rem;
  }

  .material-options {
    grid-template-columns: 1fr;
  }

  .material-option {
    min-height: 104px;
    padding-left: 66px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .material-option::before {
    top: 50%;
    transform: translateY(-50%);
  }

  .recipe-heading {
    align-items: flex-start;
    flex-direction: column;
    gap: 10px;
  }

  .recipe dl > div {
    grid-template-columns: 90px 1fr;
    gap: 12px;
  }

  .site-footer {
    min-height: 230px;
    padding: 36px 20px 96px;
    align-items: flex-start;
    flex-direction: column;
  }

  .chapter-nav {
    right: 10px;
    bottom: 10px;
    left: 10px;
    width: auto;
  }

  .chapter-nav button {
    min-height: 42px;
    padding: 0 5px;
    font-size: 8px;
    letter-spacing: -0.01em;
  }
}

@media (max-width: 390px) {
  .topology-option {
    grid-template-columns: 1fr 64px;
  }

  .topology-copy {
    display: none;
  }

  .delivery-actions {
    grid-template-columns: 1fr;
  }

  .action-button {
    border-right: 0;
    border-bottom: 1px solid var(--line-strong);
  }

  .action-button:last-child {
    border-bottom: 0;
  }
}

@media (prefers-reduced-transparency: reduce) {
  .topbar,
  .chapter-nav {
    background: var(--bg);
    backdrop-filter: none;
    -webkit-backdrop-filter: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}