.site-header {
  background: var(--header-bg);
  border-bottom: var(--control-border-width, 1px) solid var(--line);
}

.site-header-inner,
.site-footer-inner {
  max-width: 1440px;
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: center;
  flex-wrap: wrap;
}

.site-mark {
  color: inherit;
  text-decoration: none;
  display: grid;
}

.site-mark strong {
  font-family: var(--serif);
  font-size: 1.05rem;
}

.site-header-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: center;
}

.theme-picker {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--ink-soft);
}

.theme-picker select {
  appearance: none;
  box-sizing: border-box;
  height: var(--control-h);
  font: inherit;
  color: var(--ink);
  background: var(--raised);
  border: var(--control-border-width, 1px) solid var(--line);
  border-radius: 999px;
  padding: 0 1.8rem 0 0.75rem;
  background-image: linear-gradient(45deg, transparent 50%, var(--ink) 50%),
    linear-gradient(135deg, var(--ink) 50%, transparent 50%);
  background-position: calc(100% - 14px) 50%, calc(100% - 9px) 50%;
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
  cursor: pointer;
}

.site-nav,
.site-footer nav {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.site-nav a,
.site-footer a {
  color: var(--ink-soft);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.92rem;
}

.site-nav a.is-active,
.site-nav a:hover,
.site-footer a:hover {
  color: var(--ink);
}

.site-footer {
  border-top: 1px solid var(--line);
  margin-top: 40px;
  color: var(--ink-soft);
  font-size: 0.88rem;
}

#outlet {
  max-width: 1440px;
  margin: 0 auto;
  padding: 28px 20px 12px;
  min-height: calc(100vh - 180px);
}

.section {
  margin-bottom: 40px;
}

.values-card .debug {
  white-space: normal;
  margin-top: 10px;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(220px, 0.8fr);
  gap: 28px;
  align-items: center;
  margin-bottom: 36px;
}

.hero h1 {
  font-size: clamp(1.8rem, 3vw, 2.8rem);
  letter-spacing: -0.03em;
  margin-bottom: 10px;
}

.lede {
  color: var(--ink-soft);
  max-width: 38em;
  line-height: 1.5;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.btn.ghost-paper {
  background: var(--raised);
  color: var(--ink);
  border: var(--control-border-width, 1px) solid var(--line);
}

.btn.ghost-paper:hover {
  background: var(--raised-hover);
}

a.btn.ghost-paper.action-go {
  border-color: color-mix(in srgb, var(--teal) 40%, var(--line));
}

.hero-visual {
  position: relative;
  aspect-ratio: 320 / 180;
  min-height: 180px;
  background: var(--hero-visual);
  border-radius: 18px;
  border: 1px solid var(--line);
  overflow: hidden;
}

.hero-visual canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.hero-reel-copy {
  position: absolute;
  top: 14px;
  left: 16px;
  z-index: 1;
  text-decoration: none;
  color: inherit;
  text-shadow: 0 1px 0 color-mix(in srgb, var(--paper) 70%, transparent);
  transition: opacity 0.45s ease, transform 0.45s ease;
}

.hero-reel-copy .kicker {
  margin: 0 0 2px;
}

.hero-reel-title {
  margin: 0;
  font-family: var(--serif);
  font-size: 1.15rem;
  letter-spacing: -0.02em;
}

.hero-reel-copy:hover .hero-reel-title,
.hero-reel-copy:focus-visible .hero-reel-title {
  color: var(--accent-dark);
}

.hero-reel-copy:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 3px;
  border-radius: 6px;
}

.hero-reel-dots {
  position: absolute;
  left: 50%;
  bottom: 12px;
  transform: translateX(-50%);
  z-index: 1;
  display: flex;
  gap: 7px;
}

.hero-reel-dot {
  width: 8px;
  height: 8px;
  padding: 0;
  border: 0;
  border-radius: 999px;
  background: rgba(27, 36, 48, 0.28);
  cursor: pointer;
  transition: width 0.4s ease, background 0.4s ease, transform 0.4s ease;
}

.hero-reel-dot.is-active {
  width: 22px;
  background: var(--accent);
}

.hero-reel-dot:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 2px;
}

@media (prefers-reduced-motion: reduce) {
  .hero-reel-copy,
  .hero-reel-dot {
    transition: none;
  }
}

.section-head {
  margin-bottom: 14px;
}

.section-head p,
.page-head p {
  color: var(--ink-soft);
  max-width: 46em;
  line-height: 1.45;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
}

.module-card,
.featured-card,
.legacy-note {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  color: inherit;
  text-decoration: none;
  display: grid;
  gap: 8px;
}

.module-card h3,
.featured-card h2 {
  margin: 0;
}

.module-card p,
.featured-card p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 0.92rem;
  line-height: 1.4;
}

.module-meta,
.card-cta {
  font-size: 0.82rem;
  font-weight: 700;
}

.card-cta {
  color: var(--accent-dark);
}

.module-card.is-disabled {
  opacity: 0.72;
}

.progress-track {
  height: 6px;
  background: var(--line);
  border-radius: 99px;
  overflow: hidden;
}

.progress-track span {
  display: block;
  height: 100%;
  background: var(--teal);
}

.featured-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin: 28px 0 8px;
}

.page-head {
  margin-bottom: 22px;
}

.page-head h1 {
  margin: 4px 0 8px;
}

.library-module {
  margin-bottom: 22px;
}

.library-mod-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: baseline;
  margin-bottom: 8px;
}

.topic-list {
  list-style: none;
  margin: 0;
  padding: 0;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.topic-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto auto;
  gap: 12px;
  align-items: center;
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
}

.topic-row:last-child {
  border-bottom: 0;
}

.topic-row.is-planned {
  opacity: 0.78;
}

.badge {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 0.2rem 0.5rem;
  border-radius: 999px;
  border: 1px solid var(--line);
  white-space: nowrap;
}

.badge-available {
  color: var(--ok);
  border-color: var(--ok);
  background: var(--inset-ok);
}

.badge-planned,
.badge-coming-soon,
.badge-in-development {
  color: var(--ink-soft);
}

.sim-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: flex-start;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.objective {
  color: var(--ink-soft);
  max-width: 46em;
  margin: 6px 0 0;
}

.sim-toolbar {
  display: flex;
  gap: 8px;
  align-items: center;
}

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

.icon-toolbar {
  display: flex;
  gap: 6px;
  align-items: center;
  height: var(--control-h);
}

.download-menu {
  display: flex;
  align-items: center;
  position: relative;
}

.icon-btn {
  appearance: none;
  width: var(--control-h);
  height: var(--control-h);
  padding: 0;
  border-radius: 10px;
  border: var(--control-border-width, 1px) solid var(--line);
  background: var(--raised);
  color: var(--ink);
  display: grid;
  place-items: center;
  cursor: pointer;
}

.icon-btn svg {
  width: 18px;
  height: 18px;
}

.icon-btn:hover {
  background: var(--raised-hover);
  border-color: var(--accent);
}

.icon-btn.action-reset {
  border-color: color-mix(in srgb, var(--accent) 42%, var(--line));
}

.icon-btn.action-reset:hover:not(:disabled) {
  color: var(--accent-dark);
}

.icon-btn.action-download {
  border-color: color-mix(in srgb, var(--teal) 42%, var(--line));
}

.icon-btn.action-download:hover:not(:disabled) {
  color: var(--teal);
}

.icon-btn.action-fullscreen:hover:not(:disabled) {
  color: var(--teal);
}

.icon-btn:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 2px;
}

.icon-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.download-pop {
  position: absolute;
  right: 0;
  top: calc(100% + 6px);
  min-width: 11.5rem;
  background: var(--raised);
  border: 1px solid var(--line);
  border-radius: 10px;
  box-shadow: 0 10px 24px rgba(27, 36, 48, 0.12);
  z-index: 30;
  overflow: hidden;
}

.download-pop button {
  appearance: none;
  display: block;
  width: 100%;
  border: 0;
  background: none;
  text-align: left;
  padding: 0.55rem 0.8rem;
  font: inherit;
  font-weight: 600;
  font-size: 0.88rem;
  color: var(--ink);
  cursor: pointer;
}

.download-pop button:hover {
  background: var(--raised-hover);
}

#page-root {
  min-height: 100%;
}

html:fullscreen #page-root,
html:-webkit-full-screen #page-root,
html.is-fullscreen #page-root,
#page-root:fullscreen,
#page-root:-webkit-full-screen,
#page-root.is-fullscreen {
  background-color: var(--paper) !important;
  color: var(--ink) !important;
  overflow: visible !important;
  width: 100% !important;
  height: auto !important;
  max-width: none !important;
  max-height: none !important;
  min-height: 100% !important;
  box-sizing: border-box !important;
}

:root:fullscreen,
:root:-webkit-full-screen {
  background-color: var(--paper) !important;
  color: var(--ink) !important;
  overflow: auto !important;
  height: auto !important;
  max-height: none !important;
  min-height: 100% !important;
}

:fullscreen::backdrop,
:-webkit-full-screen::backdrop {
  background-color: var(--paper);
}

.notes-card h3 {
  margin: 12px 0 4px;
  font-size: 0.95rem;
}

.notes-card p {
  margin: 0 0 8px;
  color: var(--ink-soft);
  line-height: 1.45;
}

.sim-1d-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 16px;
  align-items: start;
}

.track-card {
  background: var(--stage-bg);
  border-radius: 18px;
  overflow: hidden;
}

#axis-canvas {
  display: block;
  width: 100%;
  height: 240px;
  cursor: grab;
}

.track-help,
.track-controls {
  padding: 10px 14px;
  color: var(--well-ink);
}

.track-help {
  font-size: 0.86rem;
  color: var(--well-soft);
}

.track-controls .control-head {
  color: var(--well-ink);
}

.nudge-row,
.panel-toggles {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-top: 10px;
}

.nudge-row.motion-inputs:has(.pos-input) {
  align-items: flex-end;
}

.nudge-row .switch {
  min-height: var(--control-h);
  display: inline-flex;
  align-items: center;
}

.pos-input {
  display: flex;
  gap: 6px;
  align-items: center;
  font-size: 0.88rem;
}

.pos-input input,
.pos-input select {
  box-sizing: border-box;
  height: var(--control-h);
  padding: 0 0.5rem;
  line-height: 1.15;
}

.pos-input input {
  width: 5.2rem;
}

.pos-input select {
  width: auto;
  min-width: 5.2rem;
}

.panel-toggles .switch {
  color: var(--well-ink);
}

.tag,
.tag-scalar {
  font-size: 0.68rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-weight: 700;
  margin-left: 6px;
}

.tag-scalar {
  color: var(--ink-soft);
}

.dir-glyph {
  font-weight: 700;
}

.prose h2 {
  margin: 16px 0 6px;
}

.prose p {
  color: var(--ink-soft);
  line-height: 1.5;
}

.how-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 12px;
}

.how-card {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
}

.how-card p {
  margin: 0;
  color: var(--ink-soft);
  line-height: 1.45;
  font-size: 0.92rem;
}

.lab-steps {
  margin: 0;
  padding-left: 1.2rem;
  max-width: 52em;
  color: var(--ink-soft);
  line-height: 1.55;
}

.lab-steps li {
  margin-bottom: 8px;
}

.lab-steps strong {
  color: var(--ink);
}

.track-stage {
  height: auto;
  min-height: 0;
  max-height: none;
}

.track-stage #axis-canvas {
  flex: none;
  height: 240px;
  background: transparent;
}

.motion-stage #axis-canvas {
  height: 280px;
}

.relative-stage #axis-canvas {
  height: 320px;
}

.system-stage #axis-canvas {
  height: 360px;
}

.fbd-stage #axis-canvas,
.secondlaw-stage #axis-canvas,
.firstlaw-stage #axis-canvas,
.friction-stage #axis-canvas,
.spring-stage #axis-canvas,
.work-stage #axis-canvas,
.variable-stage #axis-canvas {
  height: 340px;
}

.graph-fx-wrap #graph-fx-canvas {
  height: 280px;
  width: 100%;
  display: block;
}

.gravity-stage #axis-canvas {
  height: 360px;
}

.circle-stage #axis-canvas {
  height: 420px;
}

.thirdlaw-stage #axis-canvas {
  height: 340px;
}

.fbd-pair {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.why-cancel {
  margin-top: 12px;
  color: var(--ink-soft);
  font-size: 0.92rem;
  line-height: 1.45;
}

.why-cancel summary {
  cursor: pointer;
  font-weight: 700;
  color: var(--ink);
}

.why-cancel p {
  margin: 8px 0 0;
}

.eq-status {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
  padding: 0.7rem 0.85rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  margin: 0.35rem 0 0.7rem;
  background: var(--panel);
}

.eq-status strong {
  letter-spacing: 0.04em;
}

.eq-status.is-eq {
  background: color-mix(in srgb, var(--ok) 14%, var(--panel));
}

.eq-status.is-uneq {
  background: color-mix(in srgb, var(--accent) 14%, var(--panel));
}

.conn-cards {
  display: grid;
  gap: 0.55rem;
  margin-top: 0.8rem;
}

.conn-card {
  margin: 0;
  padding: 0.65rem 0.75rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  font-size: 0.9rem;
  background: var(--field-bg);
}

.graph-hover {
  margin: 0 0 0.6rem;
  font-family: "IBM Plex Mono", monospace;
  font-size: 0.86rem;
}

.challenge-choices {
  margin: 10px 0;
  flex-wrap: wrap;
}

.fbd-diagram canvas {
  height: 240px;
}

.force-table-wrap {
  margin-top: 10px;
  overflow-x: auto;
}

.force-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  color: var(--well-ink);
}

.force-table th,
.force-table td {
  text-align: left;
  padding: 6px 8px;
  border-bottom: var(--control-border-width, 1px) solid var(--well-line);
  vertical-align: middle;
}

.force-table th {
  font-size: 0.72rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--well-soft);
}

.force-table input[type="number"],
.force-table select,
.add-force-row select {
  box-sizing: border-box;
  width: auto;
  height: var(--control-h);
  padding: 0 0.5rem;
  font: inherit;
  max-width: 100%;
  line-height: 1.15;
}

.force-table .force-mag {
  width: 5.5rem;
}

.force-enable {
  display: flex;
  gap: 8px;
  align-items: center;
}

.force-list-head {
  margin: 12px 0 6px;
  font-size: 0.92rem;
}

.fbd-toggles {
  gap: 14px 18px;
}

.track-controls .planet-bg-switch {
  margin-top: 8px;
  color: var(--well-ink);
}

.planet-chips {
  flex-wrap: wrap;
}

.force-table .text-link {
  color: var(--accent);
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
  font: inherit;
}

.system-diagram canvas {
  height: 200px;
}

.diagram-wrap canvas {
  display: block;
  width: 100%;
  height: 160px;
  background: transparent;
}

.transport .chip {
  border-color: var(--well-line);
  background: var(--well-btn);
  color: var(--well-ink);
}

.sim-nav {
  margin: 8px 0 0;
  font-size: 0.9rem;
}

.sim-nav a {
  color: var(--accent-dark);
  text-decoration: none;
  font-weight: 600;
}

.sim-nav a:hover {
  text-decoration: underline;
}

.sim-nav .muted {
  font-weight: 600;
}

.metrics-wide {
  grid-template-columns: 1fr 1fr;
}

.graph-toggles {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 18px;
  margin: 0 0 10px;
  font-size: 0.9rem;
}

.graphs.graphs-three {
  grid-template-columns: 1fr 1fr 1fr;
}

.graphs.graphs-four {
  grid-template-columns: 1fr 1fr;
}

.invest-linearize {
  margin: 0 0 16px;
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
}

.compare-table th,
.compare-table td {
  text-align: left;
  padding: 8px 10px;
  border-bottom: 1px solid var(--line);
}

.compare-table th {
  font-size: 0.78rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--muted);
}

.motion-inputs .pos-input {
  flex-wrap: wrap;
  align-items: center;
  color: var(--well-ink);
}

.motion-inputs .pos-input::before {
  content: "";
  flex: 1 0 100%;
  order: 1;
  height: 0;
}

.motion-inputs .pos-input input,
.motion-inputs .pos-input select {
  order: 2;
}

.motion-inputs .pos-input span {
  order: 3;
}

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

.sim-shell .workspace {
  margin-bottom: 16px;
}

.about-tools .card {
  max-width: 52em;
}

.faq-list {
  display: grid;
  gap: 8px;
  max-width: 52em;
}

.faq-item {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.faq-item summary {
  cursor: pointer;
  font-weight: 600;
  padding: 12px 16px;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

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

.faq-item summary::after {
  content: "";
  width: 0.42rem;
  height: 0.42rem;
  border-right: 2px solid var(--accent);
  border-bottom: 2px solid var(--accent);
  transform: rotate(45deg);
  flex: none;
  transition: transform 0.18s ease;
}

.faq-item[open] summary::after {
  transform: rotate(225deg);
}

.faq-item[open] summary {
  color: var(--accent-dark);
}

.faq-item p {
  margin: 0;
  padding: 0 16px 14px;
  color: var(--ink-soft);
  line-height: 1.5;
}

@media (prefers-reduced-motion: reduce) {
  .faq-item summary::after {
    transition: none;
  }
}

@media (max-width: 1100px) {
  .hero,
  .featured-row,
  .sim-1d-layout {
    grid-template-columns: 1fr;
  }

  .graphs.graphs-three,
  .graphs.graphs-four,
  .metrics-wide,
  .fbd-pair {
    grid-template-columns: 1fr;
  }
}