:root {
  /* Tactile Studio Monochrome Carbon + Single Signal Accent (Zero AI-Slop Rainbow) */
  --bg: #09090b;
  --bg-panel: #0d0d10;
  --surface: #141418;
  --surface-elevated: #1c1c21;
  --text: #f4f4f5;
  --muted: #a1a1aa;
  --dim: #71717a;
  --border: rgba(255, 255, 255, 0.1);
  --border-strong: rgba(255, 255, 255, 0.22);
  --signal: #e84e36;
  --signal-soft: rgba(232, 78, 54, 0.14);
  --ivory: #f4f4f5;
  --serif: 'Instrument Serif', Georgia, serif;
  --sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: 'JetBrains Mono', monospace;
  --mobile-dock-h: 136px;
  --mobile-stage-h: 38vh;
}

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

html {
  scroll-snap-type: y mandatory;
  scroll-behavior: smooth;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
}

body {
  background: var(--bg);
  overflow-x: hidden;
  padding-left: env(safe-area-inset-left);
  padding-right: env(safe-area-inset-right);
}

/* Two-Column Split Layout: Left Explains (100vh snap screens), Right 3D Stage (Sticky 100vh) */
.split-layout {
  display: grid;
  grid-template-columns: minmax(360px, 41vw) 1fr;
  width: 100%;
  position: relative;
}

/* Left Column: Concise Explanations + Persistent Live Sentence Dock */
.explain-column {
  position: relative;
  z-index: 10;
  border-right: 1px solid var(--border);
  background: var(--bg);
}

/* Sticky Live Sentence Input Dock at top of Left Column */
.sentence-dock {
  position: sticky;
  top: 0;
  z-index: 25;
  padding: 14px clamp(20px, 3.5vw, 52px) 12px;
  background: rgba(9, 9, 11, 0.94);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.dock-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--mono);
  font-size: 10.5px;
  letter-spacing: 0.04em;
  color: var(--muted);
  gap: 8px;
  flex-wrap: wrap;
}

.telemetry-indicator {
  color: var(--text);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-weight: 500;
  white-space: nowrap;
}

.telemetry-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--signal);
  flex-shrink: 0;
}

.dock-presets {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.preset-chip {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--muted);
  background: var(--surface);
  border: 1px solid var(--border);
  padding: 4px 9px;
  border-radius: 5px;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
  white-space: nowrap;
}

.preset-chip:hover {
  color: var(--text);
  border-color: var(--border-strong);
  background: var(--surface-elevated);
}

.sentence-input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

.sentence-input {
  width: 100%;
  background: var(--surface);
  border: 1px solid var(--border-strong);
  border-radius: 7px;
  padding: 9px 12px;
  font-family: var(--mono);
  font-size: 13.5px;
  font-weight: 500;
  color: var(--text);
  outline: none;
  transition: border-color 0.18s ease, background 0.18s ease;
}

.sentence-input::placeholder {
  color: var(--dim);
}

.sentence-input:focus {
  border-color: var(--text);
  background: var(--surface-elevated);
}

.token-bar {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}

.token-bar-label {
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--muted);
  margin-right: 2px;
  white-space: nowrap;
}

.token-chip {
  font-family: var(--mono);
  font-size: 11.5px;
  font-weight: 500;
  padding: 4px 9px;
  border-radius: 5px;
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--muted);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
  white-space: nowrap;
}

.token-chip:hover {
  color: var(--text);
  border-color: var(--border-strong);
}

.token-chip.focused {
  background: var(--text);
  border-color: var(--text);
  color: var(--bg);
  font-weight: 600;
}

.step-screen {
  min-height: 100vh;
  scroll-snap-align: start;
  scroll-snap-stop: always;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 64px clamp(20px, 3.5vw, 52px) 32px;
  position: relative;
}

.step-inner {
  max-width: 42ch;
  display: flex;
  flex-direction: column;
  gap: 14px;
  opacity: 0.32;
  transform: translateY(10px);
  transition: opacity 0.28s cubic-bezier(0.16, 1, 0.3, 1), transform 0.28s cubic-bezier(0.16, 1, 0.3, 1);
}

.step-screen.active .step-inner {
  opacity: 1;
  transform: translateY(0);
}

.step-kicker {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.step-kicker .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--signal);
}

.step-title {
  font-family: var(--serif);
  font-size: clamp(32px, 3.4vw, 48px);
  font-weight: 400;
  line-height: 1.06;
  letter-spacing: -0.015em;
  color: var(--text);
  text-wrap: balance;
}

.step-title em {
  font-style: italic;
  color: var(--text);
  text-decoration: underline;
  text-decoration-color: var(--signal);
  text-underline-offset: 5px;
  text-decoration-thickness: 1.5px;
}

.step-desc {
  font-size: clamp(14.5px, 1.15vw, 16px);
  line-height: 1.62;
  color: var(--muted);
  font-weight: 400;
  text-wrap: pretty;
}

.step-desc strong {
  color: var(--text);
  font-weight: 600;
}

.formula-pill {
  align-self: flex-start;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border-strong);
  padding: 7px 12px;
  border-radius: 6px;
  margin-top: 2px;
  max-width: 100%;
  overflow-x: auto;
  white-space: nowrap;
}

.scroll-cue {
  position: absolute;
  bottom: 24px;
  left: clamp(20px, 3.5vw, 52px);
  font-family: var(--mono);
  font-size: 11px;
  color: var(--dim);
  letter-spacing: 0.04em;
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Right Column: Full-Screen Sticky Three.js 3D Viewport (Matte Carbon Studio) */
.animate-column {
  position: sticky;
  top: 0;
  height: 100vh;
  width: 100%;
  overflow: hidden;
  background: var(--bg-panel);
  cursor: grab;
  user-select: none;
  touch-action: pan-y;
}

.animate-column:active {
  cursor: grabbing;
}

#webgl-container {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

#webgl-container canvas {
  width: 100% !important;
  height: 100% !important;
  display: block;
}

/* Projected 3D Labels Overlay — Tactile Monochrome + Focal Inversion */
#labels-layer {
  position: absolute;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
  z-index: 5;
}

.label-3d {
  position: absolute;
  top: 0;
  left: 0;
  transform: translate(-50%, -50%);
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  padding: 5px 9px;
  border-radius: 5px;
  background: rgba(13, 13, 16, 0.92);
  border: 1px solid rgba(255, 255, 255, 0.16);
  color: var(--text);
  white-space: nowrap;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.5);
  transition: opacity 0.16s ease;
  pointer-events: none;
}

.label-3d .sub {
  display: block;
  font-size: 9.5px;
  font-weight: 400;
  color: var(--muted);
  margin-top: 2px;
}

/* Signature Inverted Focal Label (High-Contrast Studio Alabaster on Carbon) */
.label-3d.focal {
  background: var(--text);
  border-color: var(--text);
  color: var(--bg);
  font-weight: 600;
}

.label-3d.focal .sub {
  color: #3f3f46;
}

/* Signal Accent Label (Active Focused Token / Causal Boundary) */
.label-3d.signal {
  background: rgba(20, 20, 24, 0.95);
  border-color: var(--signal);
  color: var(--text);
}

.label-3d.signal .sub {
  color: #fca5a5;
}

/* Primary Data Label */
.label-3d.primary {
  background: rgba(20, 20, 24, 0.92);
  border-color: rgba(255, 255, 255, 0.28);
  color: var(--text);
}

/* Muted / Baseline Label */
.label-3d.muted {
  background: rgba(13, 13, 16, 0.84);
  border-color: rgba(255, 255, 255, 0.09);
  color: var(--muted);
}

/* Subtle 3D Camera Hint Badge */
.stage-badge {
  position: absolute;
  bottom: 18px;
  left: 20px;
  z-index: 8;
  font-family: var(--mono);
  font-size: 10.5px;
  color: var(--muted);
  background: rgba(13, 13, 16, 0.85);
  border: 1px solid var(--border);
  padding: 5px 11px;
  border-radius: 6px;
  pointer-events: none;
  letter-spacing: 0.02em;
}

/* Minimal Vertical Progress Dots on Far Right Edge */
.progress-rail {
  position: fixed;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
  z-index: 35;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.rail-pip {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: transparent;
  border: none;
  padding: 0;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}

.rail-pip::after {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.22);
  transition: transform 0.2s ease, background 0.2s ease;
}

.rail-pip.active::after {
  background: var(--text);
  transform: scale(1.5);
}

/* ================================================================== */
/* MOBILE & TABLET PORTRAIT ADAPTATION                                */
/* ================================================================== */
@media (max-width: 900px) {
  html {
    scroll-padding-top: calc(var(--mobile-dock-h) + var(--mobile-stage-h));
  }

  .split-layout {
    display: block;
    width: 100%;
  }

  /* 1. Fixed Top Sentence Dock on Mobile */
  .sentence-dock {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--mobile-dock-h);
    z-index: 30;
    padding: 7px 12px;
    gap: 5px;
    justify-content: center;
    background: rgba(9, 9, 11, 0.96);
    border-bottom: 1px solid var(--border);
  }

  .dock-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }

  .telemetry-indicator {
    font-size: 9px;
    letter-spacing: 0.06em;
  }

  .dock-presets {
    display: flex;
    width: 100%;
    flex-wrap: nowrap;
    overflow-x: auto;
    scrollbar-width: none;
    gap: 5px;
  }

  .dock-presets::-webkit-scrollbar {
    display: none;
  }

  .preset-chip {
    padding: 3px 8px;
    font-size: 10px;
    flex-shrink: 0;
  }

  /* 16px font-size prevents iOS Safari auto-zoom on input focus */
  .sentence-input {
    font-size: 16px;
    padding: 5px 10px;
    border-radius: 6px;
  }

  .token-bar {
    flex-wrap: nowrap;
    overflow-x: auto;
    scrollbar-width: none;
    gap: 5px;
    padding-bottom: 2px;
    padding-right: 6px;
  }

  .token-bar::-webkit-scrollbar {
    display: none;
  }

  .token-bar-label {
    font-size: 9.5px;
    margin-right: 1px;
    flex-shrink: 0;
  }

  .token-chip {
    padding: 3px 7px;
    font-size: 10.5px;
    flex-shrink: 0;
  }

  /* 2. Fixed Middle 3D WebGL Stage on Mobile */
  .animate-column {
    position: fixed;
    top: var(--mobile-dock-h);
    left: 0;
    width: 100vw;
    height: var(--mobile-stage-h);
    z-index: 20;
    border-bottom: 1px solid var(--border);
  }

  .label-3d {
    font-size: 9.5px;
    padding: 3px 6px;
    border-radius: 4px;
  }

  .label-3d .sub {
    font-size: 8.5px;
    margin-top: 1px;
  }

  .label-3d.mobile-hide {
    display: none;
  }

  .stage-badge {
    display: none;
  }

  /* 3. Scrollable Bottom Story Cards on Mobile */
  .explain-column {
    margin-top: calc(var(--mobile-dock-h) + var(--mobile-stage-h));
    border-right: none;
  }

  .step-screen {
    min-height: calc(100vh - var(--mobile-dock-h) - var(--mobile-stage-h));
    min-height: calc(100dvh - var(--mobile-dock-h) - var(--mobile-stage-h));
    padding: 22px 18px 28px;
    justify-content: flex-start;
    border-bottom: 1px solid var(--border);
  }

  .step-inner {
    max-width: 100%;
    gap: 10px;
    opacity: 0.45;
    transform: none;
  }

  .step-title {
    font-size: clamp(24px, 6.2vw, 30px);
    line-height: 1.1;
  }

  .step-desc {
    font-size: 14px;
    line-height: 1.54;
  }

  .formula-pill {
    font-size: 11px;
    padding: 6px 10px;
  }

  .scroll-cue {
    position: static;
    margin-top: 6px;
    font-size: 10px;
  }

  .progress-rail {
    right: 6px;
    top: auto;
    bottom: 14px;
    transform: none;
    gap: 2px;
    background: rgba(13, 13, 16, 0.85);
    border: 1px solid var(--border);
    padding: 4px 2px;
    border-radius: 999px;
  }

  .rail-pip {
    width: 14px;
    height: 14px;
  }

  .rail-pip::after {
    width: 5px;
    height: 5px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  .step-inner,
  .preset-chip,
  .token-chip,
  .label-3d,
  .rail-pip::after {
    transition: none !important;
  }
}