:root {
  --bg: #06080f;
  --bg-elev: #0c1220;
  --bg-card: #10182a;
  --line: rgba(148, 163, 184, 0.16);
  --text: #e8eef9;
  --muted: #93a0b8;
  --cyan: #22d3ee;
  --blue: #38bdf8;
  --amber: #f59e0b;
  --gold: #fde047;
  --violet: #a78bfa;
  --rose: #fb7185;
  --emerald: #34d399;
  --p: rgba(245, 158, 11, 0.14);
  --n: rgba(56, 189, 248, 0.14);
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.45);
  --radius: 22px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: "Outfit", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(900px 500px at 12% -10%, rgba(34, 211, 238, 0.12), transparent 50%),
    radial-gradient(700px 500px at 90% 0%, rgba(167, 139, 250, 0.1), transparent 45%),
    radial-gradient(600px 400px at 50% 110%, rgba(245, 158, 11, 0.07), transparent 50%);
  z-index: 0;
}

a { color: var(--cyan); text-decoration: none; }

.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 14px 28px;
  background: rgba(6, 8, 15, 0.78);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: 0.02em;
}

.logo {
  width: 34px;
  height: 34px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--cyan), var(--violet));
  display: grid;
  place-items: center;
  font-size: 16px;
  box-shadow: 0 0 24px rgba(34, 211, 238, 0.35);
}

.nav-links {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.nav-links a {
  color: var(--muted);
  font-size: 13px;
  padding: 6px 10px;
  border-radius: 999px;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--text);
  background: rgba(255,255,255,0.05);
}

.hero {
  position: relative;
  z-index: 1;
  padding: 72px 28px 40px;
  max-width: 1280px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: 36px;
  align-items: center;
}

.kicker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--cyan);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-weight: 600;
}

.hero h1 {
  font-size: clamp(36px, 5vw, 64px);
  line-height: 1.05;
  margin: 12px 0 16px;
  letter-spacing: -0.03em;
}

.hero h1 span {
  background: linear-gradient(90deg, var(--cyan), var(--violet), var(--amber));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.lede {
  color: var(--muted);
  font-size: 18px;
  max-width: 560px;
}

.hero-actions {
  display: flex;
  gap: 12px;
  margin-top: 26px;
  flex-wrap: wrap;
}

.btn {
  border: 0;
  cursor: pointer;
  font-family: inherit;
  font-weight: 600;
  border-radius: 999px;
  padding: 12px 20px;
  font-size: 14px;
}

.btn-primary {
  background: linear-gradient(90deg, #22d3ee, #818cf8);
  color: #061018;
  box-shadow: 0 8px 28px rgba(34, 211, 238, 0.28);
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--line);
}

.hero-card {
  background: linear-gradient(180deg, rgba(16,24,42,0.9), rgba(12,18,32,0.7));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.hero-card canvas {
  display: block;
  width: 100%;
  height: 340px;
}

.theater {
  position: relative;
  z-index: 1;
  max-width: 1280px;
  margin: 0 auto 8px;
  padding: 0 28px 12px;
}

.theater .stage { border-radius: 26px; }

.theater canvas.sim {
  height: 520px;
  background:
    radial-gradient(800px 280px at 50% 0%, rgba(253, 224, 71, 0.06), transparent 50%),
    linear-gradient(90deg, rgba(245,158,11,0.08) 0 50%, rgba(56,189,248,0.08) 50% 100%),
    #070b16;
}

.scene-strip {
  display: flex;
  gap: 6px;
  padding: 10px 12px;
  border-bottom: 1px solid var(--line);
  overflow-x: auto;
}

.scene-chip {
  border: 1px solid var(--line);
  background: #141c2e;
  color: var(--muted);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 12px;
  cursor: pointer;
  white-space: nowrap;
  font-family: inherit;
}

.scene-chip.on {
  color: #061018;
  background: linear-gradient(90deg, #22d3ee, #a78bfa);
  border-color: transparent;
  font-weight: 700;
}

.caption {
  min-height: 44px;
  padding: 10px 16px 14px;
  color: var(--muted);
  font-size: 14px;
  border-top: 1px solid var(--line);
}

.caption b { color: var(--text); }

.legend {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  padding: 12px 16px 16px;
  color: var(--muted);
  font-size: 12px;
}

.dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  display: inline-block;
  margin-right: 6px;
}

.progress {
  position: relative;
  z-index: 1;
  max-width: 1280px;
  margin: 10px auto 0;
  padding: 0 28px 20px;
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 8px;
}

.step {
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 10px 12px;
  font-size: 12px;
  color: var(--muted);
}

.step b { display: block; color: var(--text); font-size: 13px; margin-bottom: 2px; }

.chapter {
  position: relative;
  z-index: 1;
  max-width: 1280px;
  margin: 0 auto;
  padding: 28px;
}

.chapter-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 24px;
  align-items: stretch;
}

.panel, .stage {
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.panel { padding: 28px; }

.badge {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 8px;
}

h2 {
  font-size: 30px;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
}

.panel p { color: var(--muted); margin-bottom: 12px; }

.formula {
  font-family: "JetBrains Mono", ui-monospace, monospace;
  background: #0a1020;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px 14px;
  color: #c7d2fe;
  font-size: 13px;
  margin: 14px 0;
  overflow-x: auto;
}

.bullets { color: var(--muted); padding-left: 18px; margin: 10px 0 16px; }
.bullets li { margin: 6px 0; }

.stage { overflow: hidden; display: flex; flex-direction: column; }

.stage-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
}

.stage-head h3 { font-size: 15px; font-weight: 600; }

.controls { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }

.controls button, .toggle {
  background: #182236;
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 12px;
  font-size: 12px;
  cursor: pointer;
  font-family: inherit;
}

.controls button.active, .toggle.on {
  background: rgba(34, 211, 238, 0.16);
  border-color: rgba(34, 211, 238, 0.45);
  color: var(--cyan);
}

.controls label {
  font-size: 12px;
  color: var(--muted);
  display: flex;
  align-items: center;
  gap: 6px;
}

canvas.sim {
  width: 100%;
  height: 380px;
  display: block;
  background:
    linear-gradient(90deg, rgba(245,158,11,0.07) 0 50%, rgba(56,189,248,0.07) 50% 100%),
    #0a1020;
}

canvas.sim.plain {
  background: #0a1020;
}

.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0;
  border-top: 1px solid var(--line);
}

.stat {
  padding: 10px 12px;
  border-right: 1px solid var(--line);
}

.stat:last-child { border-right: 0; }

.stat span {
  display: block;
  font-size: 11px;
  color: var(--muted);
}

.stat strong {
  font-family: "JetBrains Mono", monospace;
  font-size: 14px;
}

.finale .chapter-grid { grid-template-columns: 1fr; }

.finale .stage canvas.sim { height: 460px; }

.callout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 16px;
}

.callout div {
  background: #0a1020;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 14px;
}

.callout h4 { font-size: 14px; margin-bottom: 6px; }
.callout p { font-size: 13px; margin: 0; }

footer {
  position: relative;
  z-index: 1;
  max-width: 1280px;
  margin: 20px auto 40px;
  padding: 0 28px;
  color: var(--muted);
  font-size: 13px;
}

.kid-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
  margin: 16px 0 8px;
}

.kid-card {
  background: #0a1020;
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 14px;
}

.kid-card .num {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  display: grid;
  place-items: center;
  font-weight: 700;
  background: linear-gradient(135deg, #22d3ee, #818cf8);
  color: #061018;
  margin-bottom: 8px;
  font-size: 13px;
}

.kid-card h4 { font-size: 15px; margin-bottom: 6px; }
.kid-card p { font-size: 13px; color: var(--muted); margin: 0; }

.words {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 12px 0 4px;
}

.word {
  border: 1px solid var(--line);
  background: #141c2e;
  border-radius: 999px;
  padding: 6px 10px;
  font-size: 12px;
  color: var(--muted);
}

.word b { color: var(--text); }

.compare-note {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 14px;
}

.compare-note div {
  border-radius: 16px;
  padding: 14px;
  border: 1px solid var(--line);
}

.compare-note .open { background: rgba(245,158,11,0.08); }
.compare-note .closed { background: rgba(52,211,153,0.08); }

.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 10px 16px;
  border-bottom: 1px solid var(--line);
}

.toolbar .preset {
  background: #182236;
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 12px;
  font-size: 12px;
  cursor: pointer;
  font-family: inherit;
}

.toolbar .preset.on {
  background: rgba(167,139,250,0.2);
  border-color: rgba(167,139,250,0.5);
  color: #ddd6fe;
}

.feature-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 16px;
  margin-top: 16px;
}

.quiz button {
  display: block;
  width: 100%;
  text-align: left;
  margin: 6px 0;
  background: #141c2e;
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 10px 12px;
  cursor: pointer;
  font-family: inherit;
}

.quiz button.good { border-color: #34d399; background: rgba(52,211,153,0.12); }
.quiz button.bad { border-color: #fb7185; background: rgba(251,113,133,0.1); }

.journey {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 10px;
}

.journey button {
  background: #141c2e;
  color: var(--muted);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 8px 10px;
  cursor: pointer;
  font-family: inherit;
  font-size: 12px;
}

.journey button.on { color: #061018; background: linear-gradient(90deg,#22d3ee,#a78bfa); border-color: transparent; font-weight: 700; }

.narrator {
  padding: 12px 16px;
  border-top: 1px solid var(--line);
  font-size: 15px;
  min-height: 52px;
}

.narrator b { color: var(--gold); }

canvas.sim.tall { height: 480px; }

@media (max-width: 980px) {
  .hero, .chapter-grid, .progress, .callout, .finale .chapter-grid, .kid-grid, .compare-note, .feature-grid {
    grid-template-columns: 1fr;
  }
  .nav-links { display: none; }
  canvas.sim, .hero-card canvas, .finale .stage canvas.sim, canvas.sim.tall { height: 300px; }
}