/* ==========================================================================
   Emergent Humanity — Design System
   ========================================================================== */

/* ---------- Google Fonts ---------- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap');

/* ---------- Design Tokens ---------- */
:root {
  /* Backgrounds */
  --bg-deep: #080b12;
  --bg-surface: #0f1520;
  --bg-elevated: #161d2d;
  --bg-glass: rgba(15, 21, 32, 0.75);

  /* Text */
  --text-primary: #e8ecf4;
  --text-secondary: #a4abbc;
  --text-muted: #757d8f;

  /* Accents */
  --accent: #4f9cf7;
  --accent-dim: #3a7ad4;
  --accent-glow: rgba(79, 156, 247, 0.12);
  --accent-glow-strong: rgba(79, 156, 247, 0.25);

  /* Semantic */
  --node-inactive: #2a3244;
  --node-active: #4f9cf7;
  --edge-default: #1a2234;
  --edge-active: rgba(79, 156, 247, 0.35);
  --danger: #ef4444;
  --danger-glow: rgba(239, 68, 68, 0.2);
  --success: #22c55e;
  --success-glow: rgba(34, 197, 94, 0.2);
  --warning: #f59e0b;

  /* Borders */
  --border: #1e2738;
  --border-subtle: #141b28;

  /* Spacing */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 40px;
  --space-2xl: 64px;

  /* Typography */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;

  /* Radii */
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  /* Transitions */
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
  --duration-fast: 150ms;
  --duration-normal: 300ms;
  --duration-slow: 600ms;
}

/* ---------- Reset ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  font-family: var(--font-body);
  background-color: var(--bg-deep);
  color: var(--text-primary);
  line-height: 1.7;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ---------- Scroll Container ---------- */
.scroll-container {
  height: 100dvh;
  overflow-y: auto;
  overflow-x: hidden;
  scroll-snap-type: y mandatory;
}

/* ---------- Section Layout ---------- */
.section {
  height: 100dvh;
  display: grid;
  grid-template-columns: 55% 45%;
  scroll-snap-align: start;
  position: relative;
  border-bottom: 1px solid var(--border-subtle);
}

.section:last-child {
  border-bottom: none;
}

/* ---------- Visualization Pane ---------- */
.viz-pane {
  position: relative;
  background-color: var(--bg-deep);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.viz-pane canvas {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
}

/* ---------- Text Pane ---------- */
.text-pane {
  background-color: var(--bg-surface);
  padding: var(--space-2xl) var(--space-xl);
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  border-left: 1px solid var(--border);
}

.text-content {
  max-width: 520px;
  margin: auto 0;
}

.section-number {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: var(--space-md);
  opacity: 0.9;
}

/* ---------- Typography ---------- */
.section-title {
  font-size: clamp(1.6rem, 3.5vw, 2.4rem);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.2;
  margin-bottom: var(--space-lg);
  letter-spacing: -0.02em;
}

.section-subtitle {
  font-size: 1.05rem;
  font-weight: 400;
  color: var(--text-secondary);
  margin-bottom: var(--space-xl);
  line-height: 1.7;
}

.text-body {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
  line-height: 1.8;
}

.text-body:last-child {
  margin-bottom: 0;
}

.text-body strong {
  color: var(--text-primary);
  font-weight: 600;
}

.text-body em {
  color: var(--accent);
  font-style: normal;
  font-weight: 500;
}

/* ---------- Math Blocks ---------- */
.math-block {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent);
  background: var(--accent-glow);
  border: 1px solid rgba(79, 156, 247, 0.15);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-lg) 0;
  text-align: center;
  line-height: 1.6;
}

/* ---------- Insight Callout ---------- */
.insight {
  background: var(--bg-elevated);
  border-left: 3px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: var(--space-md) var(--space-lg);
  margin: var(--space-lg) 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.insight strong {
  color: var(--text-primary);
}

/* ---------- Interactive Controls ---------- */
.viz-controls {
  position: absolute;
  bottom: var(--space-lg);
  left: var(--space-lg);
  right: var(--space-lg);
  display: flex;
  gap: var(--space-sm);
  flex-wrap: wrap;
  z-index: 10;
}

.viz-btn {
  font-family: var(--font-body);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-primary);
  background: var(--bg-glass);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-out);
  white-space: nowrap;
}

.viz-btn:hover {
  background: var(--bg-elevated);
  border-color: var(--accent-dim);
  color: var(--accent);
}

.viz-btn:active {
  transform: scale(0.97);
}

.viz-btn--danger {
  border-color: rgba(239, 68, 68, 0.3);
}

.viz-btn--danger:hover {
  border-color: var(--danger);
  color: var(--danger);
  background: var(--danger-glow);
}

/* ---------- Stats Overlay ---------- */
.viz-stats {
  position: absolute;
  top: var(--space-md);
  left: var(--space-md);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  background: var(--bg-glass);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
  z-index: 10;
  line-height: 1.6;
}

.viz-stats:empty {
  display: none;
}

.viz-stats span {
  color: var(--accent);
}

/* ---------- Hint Overlay ---------- */
.viz-hint {
  position: absolute;
  top: var(--space-md);
  right: var(--space-md);
  font-size: 0.75rem;
  color: var(--text-muted);
  background: var(--bg-glass);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: var(--space-xs) var(--space-md);
  z-index: 10;
  opacity: 0.6;
  transition: opacity var(--duration-normal);
  pointer-events: none;
}

/* ---------- Slider Control ---------- */
.slider-container {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  background: var(--bg-glass);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
}

.slider-label {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  white-space: nowrap;
}

.slider-value {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent);
  min-width: 32px;
  text-align: right;
}

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100px;
  height: 4px;
  background: var(--border);
  border-radius: 2px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 14px;
  height: 14px;
  background: var(--accent);
  border-radius: 50%;
  cursor: pointer;
  transition: transform var(--duration-fast);
}

input[type="range"]::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

input[type="range"]::-moz-range-thumb {
  width: 14px;
  height: 14px;
  background: var(--accent);
  border-radius: 50%;
  border: none;
  cursor: pointer;
}

/* ---------- Switch Control ---------- */
.switch-container {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  background: var(--bg-glass);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: var(--space-sm) var(--space-md);
  cursor: pointer;
}

.switch-label {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-primary);
  user-select: none;
}

.switch-track {
  position: relative;
  width: 44px;
  height: 24px;
  background-color: var(--border);
  border-radius: 12px;
  transition: background-color var(--duration-normal) var(--ease-out);
}

.switch-input:checked + .switch-track {
  background-color: var(--accent);
}

.switch-thumb {
  position: absolute;
  top: 2px;
  left: 2px;
  width: 20px;
  height: 20px;
  background-color: white;
  border-radius: 50%;
  transition: transform var(--duration-normal) var(--ease-out);
}

.switch-input:checked + .switch-track .switch-thumb {
  transform: translateX(20px);
}

.switch-input {
  display: none;
}

/* ---------- Hero (Section 0) ---------- */
.hero {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  scroll-snap-align: start;
  overflow: hidden;
  background: var(--bg-deep);
}

.hero-title {
  font-size: clamp(2.2rem, 6vw, 4rem);
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: var(--space-lg);
  z-index: 2;
}

.hero-subtitle {
  font-size: clamp(0.95rem, 2vw, 1.2rem);
  color: var(--text-secondary);
  max-width: 500px;
  line-height: 1.7;
  z-index: 2;
  margin-bottom: var(--space-2xl);
}

.hero canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0.3;
  z-index: 1;
}

.scroll-indicator {
  position: absolute;
  bottom: var(--space-xl);
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-sm);
  z-index: 2;
  opacity: 0.8;
  animation: pulse-down 2s var(--ease-in-out) infinite;
}

.scroll-indicator-text {
  font-size: 0.7rem;
  font-weight: 500;
  color: var(--text-secondary);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.scroll-indicator-arrow {
  width: 20px;
  height: 20px;
  border-right: 2px solid var(--text-secondary);
  border-bottom: 2px solid var(--text-secondary);
  transform: rotate(45deg);
}

@keyframes pulse-down {
  0%, 100% { opacity: 0.8; transform: translateX(-50%) translateY(0); }
  50% { opacity: 1; transform: translateX(-50%) translateY(8px); }
}

/* ---------- Section Reveal Animation ---------- */
.text-pane .section-number,
.text-pane .section-title,
.text-pane .section-subtitle,
.text-pane .text-body,
.text-pane .math-block,
.text-pane .insight {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity var(--duration-slow) var(--ease-out),
              transform var(--duration-slow) var(--ease-out);
}

.section.is-visible .text-pane .section-number,
.section.is-visible .text-pane .section-title,
.section.is-visible .text-pane .section-subtitle,
.section.is-visible .text-pane .text-body,
.section.is-visible .text-pane .math-block,
.section.is-visible .text-pane .insight {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger children */
.section.is-visible .text-pane .section-number { transition-delay: 0ms; }
.section.is-visible .text-pane .section-title { transition-delay: 80ms; }
.section.is-visible .text-pane .section-subtitle { transition-delay: 160ms; }
.section.is-visible .text-pane .text-body:nth-child(4) { transition-delay: 240ms; }
.section.is-visible .text-pane .text-body:nth-child(5) { transition-delay: 300ms; }
.section.is-visible .text-pane .text-body:nth-child(6) { transition-delay: 360ms; }
.section.is-visible .text-pane .math-block { transition-delay: 400ms; }
.section.is-visible .text-pane .insight { transition-delay: 450ms; }

/* ---------- Divider ---------- */
.section-divider {
  width: 40px;
  height: 2px;
  background: var(--accent);
  opacity: 0.4;
  margin: var(--space-lg) 0;
  border-radius: 1px;
}

/* ---------- Footer ---------- */
.footer {
  text-align: center;
  padding: var(--space-xl);
  background: var(--bg-surface);
  border-top: 1px solid var(--border-subtle);
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.footer a {
  color: var(--accent);
  text-decoration: underline;
}

.footer a:hover {
  text-decoration: none;
}

/* ---------- Responsive: Tablet & Mobile ---------- */
@media (max-width: 900px) {
  .scroll-container {
    scroll-snap-type: none;
  }

  .section {
    grid-template-columns: 1fr;
    grid-template-rows: 50dvh auto;
    height: auto;
    min-height: 100dvh;
    scroll-snap-align: none;
  }

  .text-pane {
    border-left: none;
    border-top: 1px solid var(--border);
    padding: var(--space-xl) var(--space-lg);
    overflow-y: visible;
  }

  .viz-pane canvas {
    touch-action: pan-y;
  }

  .text-content {
    max-width: 100%;
  }

  .viz-controls {
    bottom: var(--space-md);
    left: var(--space-md);
    right: var(--space-md);
  }

  .viz-btn {
    font-size: 0.72rem;
    padding: 6px 10px;
  }

  .slider-container {
    flex: 1 1 100%;
  }

  input[type="range"] {
    flex: 1;
  }
}

@media (max-width: 480px) {
  .section {
    grid-template-rows: 45dvh auto;
  }

  .text-pane {
    padding: var(--space-lg) var(--space-md);
  }

  .section-title {
    font-size: 1.4rem;
  }

  .hero-title {
    font-size: 1.8rem;
  }

  .viz-hint {
    display: none;
  }
}

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

  .text-pane .section-number,
  .text-pane .section-title,
  .text-pane .section-subtitle,
  .text-pane .text-body,
  .text-pane .math-block,
  .text-pane .insight {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .scroll-indicator {
    animation: none;
  }
}

/* ---------- Scrollbar ---------- */
.scroll-container::-webkit-scrollbar {
  width: 6px;
}

.scroll-container::-webkit-scrollbar-track {
  background: var(--bg-deep);
}

.scroll-container::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

.scroll-container::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}

/* ---------- Audio Controls ---------- */
.audio-controls {
  position: fixed;
  bottom: var(--space-lg);
  right: var(--space-lg);
  z-index: 1000;
}

.audio-btn {
  background: var(--bg-glass);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border);
  color: var(--text-primary);
  padding: var(--space-sm) var(--space-md);
  border-radius: 20px;
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.audio-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  transform: translateY(-2px);
}

.audio-btn.playing {
  border-color: var(--primary);
  box-shadow: 0 0 15px rgba(79, 156, 247, 0.3);
}