:root {
  --paper-bg: #f6f1e6;
  --paper-warm: #efe8d8;
  --ink-dark: #1d222b;
  --ink-muted: #525866;
  --ink-soft: #7b818f;
  --crayon-red: #d94e34;
  --crayon-blue: #2b6cb0;
  --crayon-green: #2b8a58;
  --crayon-amber: #d9822b;
  --crayon-purple: #7c4dff;
  --crayon-gold: #c78d20;
  --card-bg: rgba(251, 248, 241, 0.86);
  --card-border: rgba(45, 52, 64, 0.14);
  --dock-bg: rgba(28, 32, 40, 0.90);
  --dock-text: #f5f2eb;
  --font-serif: 'Cormorant Garamond', Georgia, serif;
  --font-sans: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-hand: 'Caveat', cursive;
}

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

html, body {
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  background-color: var(--paper-bg);
  color: var(--ink-dark);
  font-family: var(--font-sans);
  user-select: none;
  -webkit-font-smoothing: antialiased;
}

#stage {
  position: relative;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  background:
    radial-gradient(circle at 38% 48%, rgba(255, 253, 248, 0.65) 0%, rgba(238, 230, 212, 0.85) 100%);
}

/* Subtle paper grain overlay */
#stage::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 3;
  opacity: 0.25;
  background-image:
    repeating-linear-gradient(0deg, rgba(0,0,0,0.015) 0px, rgba(0,0,0,0.015) 1px, transparent 1px, transparent 3px),
    repeating-linear-gradient(90deg, rgba(0,0,0,0.01) 0px, rgba(0,0,0,0.01) 1px, transparent 1px, transparent 4px);
}

#gl-canvas,
#sketch-canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: block;
}

#gl-canvas {
  z-index: 1;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.8s cubic-bezier(0.22, 1, 0.36, 1);
}

#gl-canvas.active {
  opacity: 1;
}

#sketch-canvas {
  z-index: 2;
}

/* Header & Fancy Subtitle (top-left, unobstructed, no top nav) */
#top-brand {
  position: absolute;
  top: 26px;
  left: 36px;
  z-index: 10;
  max-width: 680px;
  pointer-events: none;
}

.brand-eyebrow {
  font-family: var(--font-hand);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--crayon-red);
  letter-spacing: 0.03em;
  margin-bottom: 2px;
}

.brand-title {
  font-family: var(--font-serif);
  font-size: clamp(1.9rem, 2.5vw, 2.65rem);
  font-weight: 700;
  line-height: 1.06;
  color: var(--ink-dark);
  letter-spacing: -0.01em;
}

.brand-subtitle {
  margin-top: 5px;
  font-family: var(--font-serif);
  font-style: italic;
  font-size: clamp(1.02rem, 1.25vw, 1.22rem);
  color: var(--ink-muted);
  line-height: 1.3;
}

/* Calm Right-Hand Narrative Panel that smoothly glides in/out */
#narrative-panel {
  position: absolute;
  top: 50%;
  right: 34px;
  transform: translateY(-54%);
  width: clamp(320px, 26vw, 420px);
  z-index: 10;
  pointer-events: auto;
}

.narrative-card {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--card-border);
  border-radius: 18px;
  padding: 26px 28px;
  box-shadow:
    0 18px 40px rgba(29, 34, 43, 0.07),
    0 2px 6px rgba(29, 34, 43, 0.04);
  transition:
    opacity 0.55s cubic-bezier(0.22, 1, 0.36, 1),
    transform 0.55s cubic-bezier(0.22, 1, 0.36, 1);
  opacity: 1;
  transform: translateX(0);
}

.narrative-card.glide-out {
  opacity: 0;
  transform: translateX(36px);
}

.chapter-badge {
  display: inline-block;
  font-family: var(--font-hand);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--crayon-blue);
  background: rgba(43, 108, 176, 0.09);
  padding: 2px 12px;
  border-radius: 999px;
  margin-bottom: 10px;
}

.narrative-heading {
  font-family: var(--font-serif);
  font-size: 1.65rem;
  font-weight: 700;
  color: var(--ink-dark);
  line-height: 1.18;
  margin-bottom: 12px;
}

.narrative-body {
  font-size: 0.95rem;
  line-height: 1.62;
  color: #2f3542;
}

.narrative-body p + p {
  margin-top: 10px;
}

.narrative-body strong {
  color: var(--ink-dark);
  font-weight: 600;
}

.crayon-pill {
  display: inline-block;
  padding: 0 7px;
  border-radius: 5px;
  font-weight: 600;
  font-size: 0.88em;
}

.pill-red { background: rgba(217, 78, 52, 0.14); color: #b5361e; }
.pill-blue { background: rgba(43, 108, 176, 0.14); color: #1e5288; }
.pill-green { background: rgba(43, 138, 88, 0.14); color: #1d6b42; }
.pill-amber { background: rgba(217, 130, 43, 0.16); color: #9c5611; }

.narrative-math-note {
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1.5px dashed rgba(29, 34, 43, 0.16);
  font-family: var(--font-hand);
  font-size: 1.28rem;
  line-height: 1.32;
  color: #2b3340;
}

/* Subtle bottom-left status hint */
.interaction-hint {
  position: absolute;
  bottom: 24px;
  left: 36px;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 0.8rem;
  color: var(--ink-muted);
  background: rgba(251, 248, 241, 0.75);
  padding: 6px 13px;
  border-radius: 999px;
  border: 1px solid rgba(29, 34, 43, 0.1);
  pointer-events: none;
}

.hint-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--crayon-green);
  box-shadow: 0 0 0 3px rgba(43, 138, 88, 0.2);
}

/* Bottom-center Video Player & Chapter Scrubber */
#player-dock {
  position: absolute;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 20;
  width: clamp(540px, 52vw, 780px);
  background: var(--dock-bg);
  color: var(--dock-text);
  border-radius: 999px;
  padding: 8px 16px;
  box-shadow:
    0 14px 34px rgba(15, 18, 24, 0.26),
    0 0 0 1px rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(14px);
}

.player-controls-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

.ctrl-btn {
  background: transparent;
  color: var(--dock-text);
  border: none;
  border-radius: 999px;
  width: 34px;
  height: 34px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background 0.18s ease, transform 0.12s ease;
  flex-shrink: 0;
}

.ctrl-btn:hover {
  background: rgba(255, 255, 255, 0.12);
}

.ctrl-btn:active {
  transform: scale(0.95);
}

.play-primary {
  width: 40px;
  height: 40px;
  background: var(--crayon-red);
  color: #fff;
}

.play-primary:hover {
  background: #e55a40;
}

.timeline-wrapper {
  position: relative;
  flex: 1;
  height: 24px;
  display: flex;
  align-items: center;
}

.chapter-segments {
  position: absolute;
  left: 0;
  right: 0;
  height: 6px;
  display: flex;
  gap: 3px;
  pointer-events: none;
}

.seg-bar {
  flex: 1;
  height: 100%;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 3px;
  overflow: hidden;
  position: relative;
}

.seg-fill {
  height: 100%;
  width: 0%;
  background: #f59e0b;
  border-radius: 3px;
}

#timeline-slider {
  position: relative;
  width: 100%;
  height: 24px;
  margin: 0;
  opacity: 0;
  cursor: pointer;
  z-index: 2;
}

.time-readout {
  font-size: 0.78rem;
  font-variant-numeric: tabular-nums;
  color: rgba(245, 242, 235, 0.78);
  white-space: nowrap;
  padding: 0 4px;
}

.time-sep {
  margin: 0 2px;
  opacity: 0.5;
}

.chapter-picker-btn {
  width: auto;
  padding: 0 12px;
  gap: 6px;
  font-size: 0.8rem;
  font-weight: 500;
  background: rgba(255, 255, 255, 0.1);
}

/* Chapter Popover Menu */
.chapter-popover {
  position: absolute;
  bottom: calc(100% + 12px);
  left: 0;
  right: 0;
  background: rgba(24, 28, 36, 0.96);
  backdrop-filter: blur(16px);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 18px;
  padding: 14px 16px;
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.4);
  transition: opacity 0.2s ease, transform 0.2s ease;
}

.chapter-popover.hidden {
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
}

.popover-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-size: 0.8rem;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.9);
  padding-bottom: 10px;
  margin-bottom: 10px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.popover-sub {
  font-weight: 400;
  font-size: 0.73rem;
  color: rgba(255, 255, 255, 0.55);
}

.chapter-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 6px;
  max-height: 310px;
  overflow-y: auto;
}

.chapter-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 10px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid transparent;
  color: var(--dock-text);
  text-align: left;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease;
}

.chapter-item:hover {
  background: rgba(255, 255, 255, 0.1);
}

.chapter-item.active {
  background: rgba(217, 78, 52, 0.22);
  border-color: rgba(217, 78, 52, 0.6);
}

.chap-num {
  font-family: var(--font-hand);
  font-size: 1.1rem;
  font-weight: 700;
  color: #f59e0b;
  min-width: 24px;
}

.chap-meta {
  display: flex;
  flex-direction: column;
}

.chap-title {
  font-size: 0.8rem;
  font-weight: 600;
}

.chap-tag {
  font-size: 0.68rem;
  color: rgba(255, 255, 255, 0.55);
}

/* Bottom-right citation footer referencing UiO AST2000 article */
#uio-footer {
  position: absolute;
  bottom: 18px;
  right: 28px;
  z-index: 15;
  font-size: 0.74rem;
  color: var(--ink-muted);
  background: rgba(251, 248, 241, 0.82);
  padding: 5px 12px;
  border-radius: 999px;
  border: 1px solid rgba(29, 34, 43, 0.1);
  display: flex;
  align-items: center;
  gap: 6px;
}

#uio-footer a {
  color: var(--crayon-blue);
  font-weight: 600;
  text-decoration: none;
}

#uio-footer a:hover {
  text-decoration: underline;
}

@media (max-width: 1150px) {
  #narrative-panel {
    width: 310px;
    right: 16px;
  }
  #player-dock {
    width: 480px;
  }
  .interaction-hint {
    display: none;
  }
}