@font-face {
  font-family: "Carlito";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: local("Carlito"), url("../fonts/carlito-latin-400.woff2") format("woff2");
}

@font-face {
  font-family: "Carlito";
  font-style: normal;
  font-weight: 700;
  font-display: swap;
  src: local("Carlito Bold"), local("Carlito-Bold"), url("../fonts/carlito-latin-700.woff2") format("woff2");
}

:root {
  color-scheme: dark;
  --font-sans: "Carlito", "Calibri", "Segoe UI", Arial, sans-serif;
  --bg: #050d14;
  --surface: #0a1722;
  --surface-2: #102334;
  --surface-3: #173047;
  --text: #f2f8ff;
  --muted: #9db0c4;
  --line: rgba(157, 176, 196, 0.2);
  --accent: #6ee7d2;
  --accent-2: #7fa8ff;
  --warm: #ffbf69;
  --danger: #ff7b8b;
  --purple: #bd8cff;
  --radius: 24px;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.34);
  --body-glow-a: rgba(110, 231, 210, 0.14);
  --body-glow-b: rgba(127, 168, 255, 0.14);
  --hero-bg: linear-gradient(120deg, rgba(13, 33, 47, 0.98), rgba(7, 18, 29, 0.96));
  --hero-grid: rgba(110, 231, 210, 0.035);
  --hero-orb: rgba(127, 168, 255, 0.15);
  --glass-bg: rgba(5, 13, 20, 0.6);
  --panel-bg: rgba(10, 23, 34, 0.76);
  --panel-strong: rgba(10, 23, 34, 0.88);
  --input-bg: rgba(5, 13, 20, 0.65);
  --overlay-bg: rgba(7, 17, 31, 0.72);
  --nav-bg: rgba(13, 27, 45, 0.84);
  --nav-bg-hover: rgba(13, 27, 45, 0.94);
  --canvas-shell: #07131d;
  --caption-bg: rgba(5, 13, 20, 0.86);
  --code-bg: rgba(7, 17, 31, 0.6);
  --dialog-backdrop: rgba(4, 10, 18, 0.72);
  --placeholder: #73879a;
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #f3f7fb;
  --surface: #ffffff;
  --surface-2: #f3f7fb;
  --surface-3: #e8f0f7;
  --text: #132536;
  --muted: #5c7084;
  --line: rgba(43, 69, 91, 0.18);
  --accent: #087e70;
  --accent-2: #3f69c7;
  --warm: #a95708;
  --danger: #c73e54;
  --purple: #754db3;
  --shadow: 0 20px 60px rgba(42, 66, 87, 0.13);
  --body-glow-a: rgba(8, 126, 112, 0.09);
  --body-glow-b: rgba(63, 105, 199, 0.09);
  --hero-bg: linear-gradient(120deg, rgba(255, 255, 255, 0.98), rgba(242, 248, 252, 0.98));
  --hero-grid: rgba(8, 126, 112, 0.055);
  --hero-orb: rgba(63, 105, 199, 0.1);
  --glass-bg: rgba(255, 255, 255, 0.74);
  --panel-bg: rgba(255, 255, 255, 0.9);
  --panel-strong: rgba(255, 255, 255, 0.96);
  --input-bg: rgba(243, 247, 251, 0.9);
  --overlay-bg: rgba(235, 242, 248, 0.88);
  --nav-bg: rgba(246, 249, 252, 0.96);
  --nav-bg-hover: #edf5f7;
  --canvas-shell: #edf3f8;
  --caption-bg: rgba(255, 255, 255, 0.9);
  --code-bg: #102033;
  --dialog-backdrop: rgba(20, 34, 48, 0.45);
  --placeholder: #788b9c;
}

* {
  box-sizing: border-box;
}

.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;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background:
    radial-gradient(circle at 12% -5%, var(--body-glow-a), transparent 30%),
    radial-gradient(circle at 88% 3%, var(--body-glow-b), transparent 28%),
    var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.5;
  letter-spacing: .002em;
}

body,
.hero,
.catalog-panel,
.visual-panel,
.explanation-panel,
.learning-map,
.metric-card,
.nav-button,
.flow-item,
.control,
.code-dialog {
  transition: background-color 180ms ease, border-color 180ms ease, color 180ms ease, box-shadow 180ms ease;
}

button,
input,
select {
  font: inherit;
}

button {
  border: 0;
  cursor: pointer;
}

button:focus,
input:focus,
select:focus,
button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.page-shell {
  width: min(1520px, calc(100% - 40px));
  margin: 0 auto;
  padding: 16px 0 28px;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(350px, 0.65fr);
  align-items: center;
  justify-content: space-between;
  gap: 36px;
  min-height: 330px;
  padding: 36px 40px;
  border: 1px solid var(--line);
  border-radius: 30px;
  background: var(--hero-bg);
  box-shadow: var(--shadow), inset 0 1px 0 rgba(255, 255, 255, .035);
  position: relative;
  overflow: hidden;
}

.hero::after {
  content: "";
  position: absolute;
  inset: 0 20% auto;
  height: 1px;
  background: linear-gradient(90deg, transparent, color-mix(in srgb, var(--accent) 48%, transparent), transparent);
  pointer-events: none;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background:
    linear-gradient(90deg, var(--hero-grid) 1px, transparent 1px),
    linear-gradient(var(--hero-grid) 1px, transparent 1px),
    radial-gradient(circle at 82% 28%, var(--hero-orb), transparent 35%);
  background-size: 44px 44px, 44px 44px, auto;
  pointer-events: none;
  opacity: 0.7;
}

.hero-content,
.hero-metrics {
  position: relative;
  z-index: 1;
}

.hero-utilities {
  position: absolute;
  top: 18px;
  right: 18px;
  z-index: 3;
  display: inline-flex;
  align-items: center;
  gap: 7px;
}

.theme-toggle,
.install-button {
  display: inline-flex;
  min-height: 38px;
  align-items: center;
  gap: 8px;
  padding: 7px 11px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--glass-bg);
  color: var(--text);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
  font-size: .75rem;
  font-weight: 800;
  backdrop-filter: blur(14px);
  transition: border-color 160ms ease, background 160ms ease, transform 120ms ease;
}

.theme-toggle:hover,
.install-button:hover {
  border-color: color-mix(in srgb, var(--accent) 55%, transparent);
  background: var(--surface-2);
  transform: translateY(-1px);
}

.theme-toggle:active,
.install-button:active {
  transform: scale(.97);
}

.install-button {
  border-color: color-mix(in srgb, var(--accent) 38%, var(--line));
  background: color-mix(in srgb, var(--accent) 12%, var(--glass-bg));
  color: var(--accent);
}

.install-button[hidden] {
  display: none;
}

.utility-icon {
  display: grid;
  width: 22px;
  height: 22px;
  place-items: center;
  border-radius: 7px;
  background: color-mix(in srgb, var(--accent) 13%, transparent);
  color: var(--accent);
  font-size: .86rem;
}

.install-icon {
  font-size: 1rem;
  line-height: 1;
  transform: translateY(-1px);
}

.hero-label {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  margin-bottom: 14px;
  color: var(--accent);
  font-size: .75rem;
  font-weight: 850;
  letter-spacing: .16em;
  text-transform: uppercase;
}

.hero-label span {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 6px rgba(110,231,210,.1), 0 0 22px rgba(110,231,210,.55);
}

.eyebrow,
.step-label,
.category {
  margin: 0 0 8px;
  color: var(--accent);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

h1,
h2,
p {
  margin-top: 0;
}

h1 {
  max-width: 900px;
  margin-bottom: 10px;
  font-size: clamp(2.7rem, 5.4vw, 5.5rem);
  line-height: 0.94;
  letter-spacing: -0.045em;
  animation: fadeInDown 0.6s ease-out;
}

.hero-copy {
  max-width: 760px;
  margin-bottom: 0;
  color: var(--muted);
  font-size: clamp(1rem, 1.4vw, 1.22rem);
  line-height: 1.55;
  animation: fadeInUp 0.6s ease-out 0.1s both;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 18px;
  margin-top: 20px;
}

.hero-link {
  display: inline-flex;
  align-items: center;
  gap: 18px;
  padding: 13px 18px;
  border-radius: 13px;
  text-decoration: none;
}

.keyboard-hint {
  color: var(--muted);
  font-size: .78rem;
}

kbd {
  display: inline-grid;
  min-width: 25px;
  height: 25px;
  margin-right: 4px;
  place-items: center;
  border: 1px solid var(--line);
  border-bottom-color: rgba(157,176,196,.4);
  border-radius: 7px;
  background: rgba(255,255,255,.04);
  color: var(--text);
  font: 700 .7rem ui-monospace, monospace;
}

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

.metric-card {
  min-height: 100px;
  padding: 17px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--glass-bg);
  backdrop-filter: blur(16px);
  transition: border-color 180ms ease, transform 180ms ease, background 180ms ease;
}

.metric-card:hover {
  transform: translateY(-2px);
  border-color: color-mix(in srgb, var(--accent) 38%, var(--line));
}

.metric-card-primary {
  grid-row: span 2;
  display: flex;
  min-height: 212px;
  flex-direction: column;
  justify-content: flex-end;
  background: linear-gradient(155deg, rgba(110,231,210,.18), rgba(127,168,255,.07));
  border-color: rgba(110,231,210,.3);
}

.metric-card strong {
  display: block;
  color: var(--text);
  font-size: 2rem;
  line-height: 1;
  letter-spacing: -.04em;
}

.metric-card-primary strong {
  color: var(--accent);
  font-size: clamp(3.5rem, 6vw, 5rem);
}

.metric-card span {
  display: block;
  margin-top: 7px;
  color: var(--muted);
  font-size: .72rem;
  font-weight: 800;
  letter-spacing: .1em;
  text-transform: uppercase;
}

.hero-badge {
  display: grid;
  flex: 0 0 150px;
  min-height: 150px;
  place-content: center;
  border: 1px solid rgba(98, 214, 197, 0.4);
  border-radius: 50%;
  background: rgba(98, 214, 197, 0.08);
  text-align: center;
  animation: pulse-glow 3s ease-in-out infinite;
  transition: all 0.3s ease;
}

.hero-badge:hover {
  transform: scale(1.05);
  border-color: rgba(98, 214, 197, 0.7);
  box-shadow: 0 0 30px rgba(98, 214, 197, 0.2);
}

.hero-badge strong {
  font-size: 3.4rem;
  line-height: 1;
  color: var(--text);
  font-weight: 900;
}

.hero-badge span {
  color: var(--muted);
  font-size: 0.83rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-top: 4px;
}

@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse-glow {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(98, 214, 197, 0.3);
  }
  50% {
    box-shadow: 0 0 20px 10px rgba(98, 214, 197, 0);
  }
}

.catalog-panel {
  margin: 14px 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel-bg);
  box-shadow: 0 16px 50px rgba(0,0,0,.2);
  backdrop-filter: blur(18px);
  scroll-margin-top: 16px;
}

.catalog-header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 12px;
}

.catalog-header h2 {
  margin: 0;
  font-size: clamp(1.45rem, 2.1vw, 2rem);
  letter-spacing: -.035em;
}

.search-box {
  display: flex;
  align-items: center;
  gap: 9px;
  width: min(320px, 100%);
  padding: 0 14px;
  border: 1px solid var(--line);
  border-radius: 13px;
  background: var(--input-bg);
  color: var(--muted);
}

.search-box:focus-within {
  border-color: rgba(110,231,210,.55);
  box-shadow: 0 0 0 3px rgba(110,231,210,.08);
}

.search-box input {
  width: 100%;
  padding: 11px 0;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--text);
}

.search-box input::placeholder {
  color: var(--placeholder);
}

.algorithm-nav {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(138px, 1fr));
  gap: 8px;
  margin-top: 10px;
}

.catalog-tabs {
  display: flex;
  gap: 6px;
  margin-top: 0;
  padding: 4px;
  width: fit-content;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--overlay-bg);
}

.catalog-tab {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid transparent;
  border-radius: 11px;
  background: transparent;
  color: var(--muted);
  font-weight: 800;
  transition: color 160ms ease, background 160ms ease, border-color 160ms ease;
}

.catalog-tab span {
  display: grid;
  min-width: 23px;
  height: 23px;
  padding: 0 7px;
  place-items: center;
  border-radius: 8px;
  background: rgba(159, 176, 197, 0.1);
  color: var(--muted);
  font-size: 0.74rem;
}

.catalog-tab:hover {
  color: var(--text);
  background: rgba(122, 162, 255, 0.08);
}

.catalog-tab.active {
  border-color: rgba(98, 214, 197, 0.42);
  background: rgba(98, 214, 197, 0.12);
  color: var(--text);
}

.catalog-tab.active span {
  background: rgba(98, 214, 197, 0.2);
  color: var(--accent);
}

.nav-button-wrap {
  position: relative;
  min-width: 0;
}

.nav-button {
  display: flex;
  min-height: 72px;
  flex-direction: column;
  justify-content: flex-end;
  width: 100%;
  height: 100%;
  padding: 11px 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--nav-bg);
  color: var(--muted);
  text-align: left;
  transition: all 160ms ease;
  position: relative;
}

.nav-button strong {
  color: inherit;
  font-size: .9rem;
}

.nav-button small {
  max-width: calc(100% - 24px);
  margin-top: 3px;
  overflow: hidden;
  color: var(--placeholder);
  font-size: .63rem;
  line-height: 1.2;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.nav-button:hover {
  transform: translateY(-2px);
  border-color: rgba(98, 214, 197, 0.5);
  background: var(--nav-bg-hover);
  box-shadow: 0 0 0 1px rgba(98, 214, 197, 0.3), 0 4px 12px rgba(98, 214, 197, 0.15);
}

.nav-button:active {
  transform: translateY(0) scale(0.98);
}

.nav-button:focus,
.nav-button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

.nav-button.active {
  border-color: rgba(98, 214, 197, 0.65);
  background: rgba(98, 214, 197, 0.11);
  color: var(--text);
  box-shadow: 0 0 0 1px rgba(98, 214, 197, 0.25), 0 0 24px rgba(98, 214, 197, 0.18);
}

.nav-button.active::after {
  content: "";
  position: absolute;
  inset: 8px auto 8px 0;
  width: 3px;
  border-radius: 0 3px 3px 0;
  background: var(--accent);
  box-shadow: 0 0 12px color-mix(in srgb, var(--accent) 60%, transparent);
}

.nav-code-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  z-index: 2;
  padding: 2px 6px;
  font-size: 0.62rem;
  line-height: 1.4;
  opacity: 0.75;
}

.nav-code-btn:hover {
  opacity: 1;
}

.nav-button .nav-index {
  display: block;
  margin-bottom: auto;
  color: var(--accent);
  font-size: 0.68rem;
  font-weight: 800;
}

.catalog-empty {
  grid-column: 1 / -1;
  margin: 0;
  padding: 28px;
  border: 1px dashed var(--line);
  border-radius: 14px;
  color: var(--muted);
  text-align: center;
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 1.65fr) minmax(380px, 0.7fr);
  gap: 14px;
  align-items: start;
}

.visual-panel,
.explanation-panel,
.learning-map {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel-strong);
  box-shadow: var(--shadow);
}

.visual-panel {
  padding: 20px;
  align-self: start;
}

.panel-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 12px;
}

.panel-heading h2,
.learning-map h2 {
  margin-bottom: 0;
  font-size: clamp(1.4rem, 2.2vw, 2.15rem);
  letter-spacing: -0.035em;
}

.canvas-mode {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: .72rem;
  font-weight: 750;
}

.canvas-mode span {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 5px rgba(110,231,210,.09);
}

.panel-actions,
.footer-nav {
  display: flex;
  gap: 10px;
}

.primary,
.secondary {
  padding: 9px 13px;
  border-radius: 12px;
  font-weight: 800;
  transition: transform 120ms ease, box-shadow 120ms ease, background 160ms ease;
}

.primary {
  background: linear-gradient(135deg, var(--accent), #8cebdc);
  color: #06131b;
}

.primary:hover {
  box-shadow: 0 0 20px rgba(98, 214, 197, 0.35);
}

.secondary {
  border: 1px solid var(--line);
  background: var(--surface-2);
  color: var(--text);
}

.secondary:hover {
  border-color: rgba(98, 214, 197, 0.5);
  background: var(--surface-3);
}

.primary:active,
.secondary:active {
  transform: scale(0.96);
}

.canvas-wrap {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 20px;
  background:
    linear-gradient(rgba(159, 176, 197, 0.055) 1px, transparent 1px),
    linear-gradient(90deg, rgba(159, 176, 197, 0.055) 1px, transparent 1px),
    var(--canvas-shell);
  background-size: 32px 32px;
  box-shadow: inset 0 0 80px rgba(4, 12, 20, .28);
}

canvas {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 49 / 30;
}

.canvas-caption {
  position: absolute;
  right: 14px;
  bottom: 14px;
  max-width: 60%;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--caption-bg);
  backdrop-filter: blur(12px);
  color: var(--muted);
  font-size: 0.78rem;
}

.playback {
  display: block;
  margin: 0;
  padding: 0;
  border: 0;
  background: transparent;
}

.playback button,
.speed-control select {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface-2);
  color: var(--text);
  font-weight: 850;
}

.playback button:hover,
.speed-control select:hover {
  border-color: rgba(110,231,210,.48);
  background: var(--surface-3);
}

.playback-icon {
  display: flex;
  min-width: 0;
  min-height: 48px !important;
  padding: 6px 4px;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1px;
  font-size: 1.15rem;
}

.playback-icon small {
  color: var(--muted);
  font-size: .6rem;
  font-weight: 750;
}

.playback-main {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  min-width: 0;
  min-height: 46px !important;
  padding: 0 15px;
  border-color: rgba(110,231,210,.38) !important;
  background: rgba(110,231,210,.13) !important;
  color: var(--accent) !important;
}

.playback-main.is-playing {
  box-shadow: 0 0 0 3px rgba(110,231,210,.08), 0 0 24px rgba(110,231,210,.12);
}

.playback-actions {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 6px;
  margin-top: 8px;
}

.timeline-block {
  margin-top: 12px;
}

.timeline-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 4px;
  color: var(--muted);
  font-size: .7rem;
  font-weight: 750;
}

.timeline-output {
  min-width: 38px;
  color: var(--muted);
  font: 750 .72rem ui-monospace, monospace;
  text-align: right;
}

.playback-tools {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin-top: 10px;
}

.speed-control {
  display: grid;
  grid-column: 1 / -1;
  gap: 4px;
}

.speed-control > span {
  color: var(--muted);
  font-size: .66rem;
  font-weight: 750;
}

.speed-control select {
  width: 100%;
  min-height: 40px;
  padding: 0 8px;
  cursor: pointer;
}

.code-action {
  display: inline-flex;
  align-self: end;
  min-height: 40px;
  padding: 0 10px;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1px solid rgba(127,168,255,.35);
  border-radius: 10px;
  background: rgba(127,168,255,.1);
  color: var(--accent-2);
  font-size: .78rem;
  font-weight: 800;
  text-decoration: none;
}

.code-action:hover {
  border-color: rgba(127,168,255,.65);
  background: rgba(127,168,255,.16);
}

.documentation-action {
  border-color: rgba(110,231,210,.35);
  background: rgba(110,231,210,.1);
  color: var(--accent);
}

.documentation-action:hover {
  border-color: rgba(110,231,210,.65);
  background: rgba(110,231,210,.16);
}

.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 8px;
  margin-top: 10px;
}

.teaching-panel .controls {
  grid-template-columns: 1fr;
}

.control {
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface-2);
  transition: border-color 160ms ease, background 160ms ease;
}

.control:hover,
.control:focus-within {
  border-color: rgba(98, 214, 197, 0.4);
  background: var(--surface-3);
}

.control-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 5px;
}

.control label {
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 700;
}

.control output {
  color: var(--text);
  font-size: 0.82rem;
  font-weight: 800;
}

input[type="range"] {
  width: 100%;
  height: 18px;
  margin: 0;
  appearance: none;
  background: transparent;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-runnable-track {
  height: 5px;
  border: 1px solid color-mix(in srgb, var(--line) 75%, transparent);
  border-radius: 999px;
  background: linear-gradient(90deg, color-mix(in srgb, var(--accent) 34%, var(--surface-3)), var(--surface-3));
}

input[type="range"]::-webkit-slider-thumb {
  width: 16px;
  height: 16px;
  margin-top: -6px;
  appearance: none;
  border: 3px solid var(--surface);
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 52%, transparent), 0 3px 10px rgba(0, 0, 0, .2);
}

input[type="range"]::-moz-range-track {
  height: 5px;
  border: 1px solid color-mix(in srgb, var(--line) 75%, transparent);
  border-radius: 999px;
  background: var(--surface-3);
}

input[type="range"]::-moz-range-progress {
  height: 5px;
  border-radius: 999px;
  background: var(--accent);
}

input[type="range"]::-moz-range-thumb {
  width: 12px;
  height: 12px;
  border: 3px solid var(--surface);
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 1px color-mix(in srgb, var(--accent) 52%, transparent);
}

.explanation-panel {
  position: sticky;
  top: 16px;
  align-self: start;
  max-height: min(760px, calc(100vh - 32px));
  padding: 0;
  overflow: hidden auto;
  scrollbar-color: var(--surface-3) transparent;
}

.lesson-overview {
  padding: 18px;
  border-bottom: 1px solid var(--line);
  background: linear-gradient(145deg, rgba(110,231,210,.055), transparent 70%);
}

.lesson-overview .summary {
  margin-bottom: 0;
}

.side-section {
  padding: 17px 18px;
  border-bottom: 1px solid var(--line);
}

.side-section-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.side-section-heading h3 {
  margin: 2px 0 0;
  color: var(--text);
  font-size: 1rem;
  letter-spacing: -.015em;
}

.section-kicker {
  color: var(--accent);
  font-size: .6rem;
  font-weight: 850;
  letter-spacing: .13em;
  text-transform: uppercase;
}

.status-pill {
  display: inline-flex;
  min-height: 25px;
  align-items: center;
  padding: 0 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(157,176,196,.07);
  color: var(--muted);
  font-size: .62rem;
  font-weight: 800;
}

.status-pill[data-state="playing"] {
  border-color: rgba(110,231,210,.4);
  background: rgba(110,231,210,.1);
  color: var(--accent);
}

.status-pill[data-state="complete"] {
  border-color: rgba(255,191,105,.4);
  background: rgba(255,191,105,.1);
  color: var(--warm);
}

.parameter-block {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.parameter-heading {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
}

.parameter-heading h4 {
  margin: 0;
  font-size: .78rem;
}

.parameter-heading span {
  color: var(--muted);
  font-size: .63rem;
}

.summary {
  margin-bottom: 16px;
  color: var(--muted);
  font-size: 1.03rem;
}

.lesson-guide .flow {
  gap: 4px;
}

.flow {
  display: grid;
  gap: 5px;
}

.flow-item {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 10px;
  padding: 10px 11px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface-2);
}

.flow-item > span {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  border-radius: 50%;
  background: rgba(98, 214, 197, 0.13);
  color: var(--accent);
  font-weight: 900;
}

.flow-item p,
.use-card p {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 0.88rem;
}

.flow-arrow {
  height: 14px;
  line-height: 14px;
  color: var(--muted);
  text-align: center;
}

.formula-card,
.use-card {
  margin-top: 10px;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--overlay-bg);
}

.lesson-navigation {
  display: grid;
  grid-template-columns: 1fr 1.25fr;
  gap: 8px;
  padding: 14px 18px 18px;
}

.lesson-navigation button {
  min-width: 0;
}

.formula-card span,
.use-card span {
  display: block;
  margin-bottom: 5px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.formula-card .math-expression {
  color: var(--warm);
  font-family: "Cambria Math", "STIX Two Math", "Latin Modern Math", "Noto Sans Math", "Times New Roman", serif;
  font-size: 1.02rem;
  font-weight: 600;
  font-variant-numeric: lining-nums;
  line-height: 1.5;
  overflow-wrap: anywhere;
}

.formula-notation {
  margin: 9px 0 0;
  padding-top: 9px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: .76rem;
  line-height: 1.45;
}

.learning-map {
  display: grid;
  grid-template-columns: minmax(260px, 0.7fr) minmax(0, 1.3fr);
  gap: 22px;
  margin-top: 14px;
  padding: 20px;
}

.learning-map ol {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 7px;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: learning;
}

.learning-map li {
  counter-increment: learning;
  display: grid;
  grid-template-columns: 32px 1fr auto;
  align-items: center;
  gap: 8px;
  padding: 8px 10px;
  border: 1px solid var(--line);
  border-radius: 12px;
  color: var(--muted);
  background: var(--surface-2);
  transition: all 160ms ease;
}

.map-lesson-button {
  min-width: 0;
  padding: 4px 0;
  border: 0;
  background: transparent;
  color: inherit;
  font-weight: 750;
  text-align: left;
}

.map-lesson-button:hover {
  color: var(--text);
}

.map-lesson-button:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

.code-btn {
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface-3);
  color: var(--accent-2);
  font-size: 0.78rem;
  font-weight: 800;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  transition: all 160ms ease;
}

.code-btn:hover {
  border-color: rgba(122, 162, 255, 0.6);
  background: rgba(122, 162, 255, 0.14);
  color: var(--text);
}

.code-btn:active {
  transform: scale(0.94);
}

.learning-map li::before {
  content: counter(learning);
  display: grid;
  width: 28px;
  height: 28px;
  place-items: center;
  border-radius: 8px;
  background: rgba(122, 162, 255, 0.14);
  color: var(--accent-2);
  font-weight: 900;
}

.learning-map li:hover {
  border-color: rgba(98, 214, 197, 0.5);
  background: var(--nav-bg-hover);
  color: var(--text);
}

.learning-map li.active {
  border-color: rgba(98, 214, 197, 0.65);
  background: rgba(98, 214, 197, 0.11);
  color: var(--text);
  box-shadow: 0 0 0 1px rgba(98, 214, 197, 0.25), 0 0 24px rgba(98, 214, 197, 0.18);
}

.learning-map li.active::before {
  background: rgba(98, 214, 197, 0.22);
  color: var(--accent);
}

.topic-directory {
  margin-top: 14px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel-strong);
  box-shadow: var(--shadow);
}

.topic-directory-header {
  display: grid;
  grid-template-columns: minmax(0, .9fr) minmax(320px, 1.1fr);
  align-items: end;
  gap: 24px;
  margin-bottom: 16px;
}

.topic-directory-header h2 {
  margin: 0;
  font-size: clamp(1.45rem, 2.1vw, 2rem);
  letter-spacing: -.035em;
}

.topic-directory-header > p {
  margin: 0;
  color: var(--muted);
  font-size: .9rem;
}

.topic-directory-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1fr;
  gap: 10px;
}

.topic-directory article {
  position: relative;
  overflow: hidden;
  padding: 15px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--surface-2);
}

.topic-directory article::before {
  content: "";
  position: absolute;
  inset: 0 18px auto;
  height: 2px;
  border-radius: 0 0 4px 4px;
  background: var(--accent);
  opacity: .7;
}

.topic-directory article:nth-child(2)::before {
  background: var(--accent-2);
}

.topic-directory article:nth-child(3)::before {
  background: var(--warm);
}

.topic-directory h3 {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin: 0;
  font-size: .94rem;
}

.topic-directory h3 span {
  color: var(--accent);
  font-size: .65rem;
  letter-spacing: .08em;
  text-transform: uppercase;
}

.topic-directory article > p {
  margin: 7px 0 12px;
  color: var(--muted);
  font-size: .76rem;
}

.topic-directory nav {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
}

.topic-directory a,
.footer-links a {
  color: var(--muted);
  text-decoration: none;
}

.topic-directory a {
  padding: 5px 8px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel-bg);
  font-size: .67rem;
  font-weight: 750;
  transition: border-color 150ms ease, color 150ms ease, background 150ms ease;
}

.topic-directory a:hover,
.topic-directory a:focus-visible {
  border-color: color-mix(in srgb, var(--accent) 55%, transparent);
  background: color-mix(in srgb, var(--accent) 10%, var(--surface-2));
  color: var(--text);
}

footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 4px 0;
  color: var(--muted);
}

footer p {
  margin-bottom: 0;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.footer-links a {
  font-size: .78rem;
  font-weight: 750;
}

.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--accent);
}

.error-page {
  display: grid;
  min-height: 100vh;
  padding: 24px;
  place-items: center;
}

.error-page main {
  width: min(680px, 100%);
  padding: clamp(28px, 6vw, 64px);
  border: 1px solid var(--line);
  border-radius: 30px;
  background: var(--panel-strong);
  box-shadow: var(--shadow);
  text-align: center;
}

.error-page h1 {
  margin-bottom: 16px;
  font-size: clamp(2rem, 6vw, 4.5rem);
}

.error-page main > p:not(.eyebrow) {
  margin: 0 auto 26px;
  color: var(--muted);
}

.error-page-link {
  display: inline-flex;
  text-decoration: none;
}

.noscript-message {
  position: fixed;
  right: 16px;
  bottom: 16px;
  z-index: 20;
  max-width: 420px;
  margin: 0;
  padding: 12px 16px;
  border: 1px solid var(--danger);
  border-radius: 12px;
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
}

.code-dialog {
  width: min(640px, calc(100% - 40px));
  padding: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
  animation: dialogIn 220ms ease;
}

.code-dialog::backdrop {
  background: var(--dialog-backdrop);
  animation: backdropIn 220ms ease;
}

@keyframes dialogIn {
  from {
    opacity: 0;
    transform: translateY(10px) scale(0.97);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes backdropIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.code-dialog-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 22px;
  border-bottom: 1px solid var(--line);
}

.code-dialog-header h3 {
  margin: 0;
  font-size: 1.1rem;
}

.code-dialog-actions {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.code-block {
  margin: 0;
  padding: 20px 22px;
  max-height: 60vh;
  overflow: auto;
  background: var(--code-bg);
}

.code-block code {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.88rem;
  line-height: 1.6;
  white-space: pre;
}

@media (max-width: 1050px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: 0;
    gap: 24px;
  }

  .hero-metrics {
    grid-template-columns: repeat(3, 1fr);
  }

  .metric-card,
  .metric-card-primary {
    grid-row: auto;
    min-height: 90px;
  }

  .metric-card-primary strong {
    font-size: 3.3rem;
  }

  .workspace,
  .learning-map,
  .topic-directory-header {
    grid-template-columns: 1fr;
  }

  .topic-directory-grid {
    grid-template-columns: 1fr;
  }

  .explanation-panel {
    position: static;
    display: block;
    max-height: none;
    overflow: visible;
  }
}

@media (max-width: 720px) {
  .page-shell {
    width: min(100% - 22px, 1480px);
    padding-top: 12px;
  }

  .hero,
  .panel-heading,
  .catalog-header,
  footer {
    align-items: flex-start;
    flex-direction: column;
  }

  .hero {
    gap: 20px;
    padding: 22px 20px;
  }

  .hero-actions {
    align-items: flex-start;
    flex-direction: column;
    gap: 10px;
  }

  .catalog-tabs {
    width: 100%;
    overflow-x: auto;
  }

  .catalog-tab {
    flex: 0 0 auto;
    justify-content: center;
    padding-inline: 10px;
    gap: 6px;
    font-size: 0.8rem;
  }

  .visual-panel,
  .learning-map,
  .topic-directory {
    padding: 14px;
  }

  .explanation-panel {
    padding: 0;
  }

  .learning-map ol {
    grid-template-columns: 1fr;
  }

  .canvas-caption {
    position: static;
    max-width: none;
    border-width: 1px 0 0;
    border-radius: 0;
  }

  canvas {
    aspect-ratio: 4 / 3;
  }

  .playback-main {
    min-width: 0;
    padding-inline: 8px;
  }

  .playback-tools {
    grid-template-columns: 1fr;
  }

  .speed-control select {
    width: 100%;
  }
}

@media (max-width: 520px) {
  .page-shell {
    width: min(100% - 16px, 1520px);
  }

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

  .hero {
    padding-top: 58px;
  }

  .hero-utilities {
    top: 14px;
    right: 14px;
  }

  .theme-toggle #themeLabel {
    display: none;
  }

  .metric-card-primary {
    grid-column: 1 / -1;
  }

  .catalog-panel {
    padding: 14px;
  }

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

  .panel-heading h2 {
    font-size: 1.5rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
}