/* ═══════════════════════════════════════════════════════
   Semantic Trajectories — 3Blue1Brown Inspired Theme
   Dark-first with light mode toggle
   ═══════════════════════════════════════════════════════ */

:root {
  --bg: #f4f4fb;
  --bg2: #eaeaf5;
  --blue: #2563eb;
  --blue-dim: #6b9ddb;
  --gold: #b8941f;
  --gold-dim: #d4b84a;
  --green: #16a34a;
  --red: #dc2626;
  --pink: #9333ea;
  --text: #1e1e3a;
  --text-dim: #5a5a78;
  --surface: rgba(0,0,0,0.04);
  --card-bg: rgba(255,255,255,0.75);
  --card-border: rgba(40,60,120,0.15);
  --diagram-bg: rgba(255,255,255,0.7);
  --grid-color: rgba(40,60,120,0.06);
  --callout-bg: rgba(184,148,31,0.06);
  --callout-border: rgba(184,148,31,0.25);
  --section-border: rgba(40,60,120,0.08);
  --shadow-glow: 0 4px 30px rgba(40,60,120,0.08);
}



/* ── BASE ── */
html { scroll-behavior: smooth; }

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

body {
  font-family: 'EB Garamond', 'Georgia', serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  line-height: 1.7;
}

/* ── Grid background ── */
.grid-bg {
  position: relative;
}
.grid-bg::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--grid-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-color) 1px, transparent 1px);
  background-size: 60px 60px;
  pointer-events: none;
  z-index: 0;
}
.grid-bg > * { position: relative; z-index: 1; }



/* ── Typography ── */
h1 { font-size: 2.8rem; font-weight: 700; line-height: 1.15; letter-spacing: -0.5px; }
h2 { font-size: 2rem; font-weight: 600; line-height: 1.25; letter-spacing: -0.3px; }
h3 { font-size: 1.3rem; font-weight: 600; color: var(--gold); margin-bottom: 10px; }
p, li { font-size: 1.1rem; line-height: 1.8; color: var(--text); }
.dim { color: var(--text-dim); }
.blue { color: var(--blue); }
.gold { color: var(--gold); }
.green { color: var(--green); }
.red { color: var(--red); }
.pink { color: var(--pink); }
.mono { font-family: 'JetBrains Mono', monospace; font-size: 0.9em; }
em { font-style: italic; color: var(--blue); }
a { color: var(--blue); text-decoration: none; transition: color 0.3s ease; }
a:hover { color: var(--gold); }

/* ── Section tag badge ── */
.tag-badge {
  display: inline-block;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  font-weight: 500;
  letter-spacing: 2.5px;
  text-transform: uppercase;
  color: var(--gold);
  border: 1px solid var(--gold-dim);
  padding: 4px 16px;
  border-radius: 30px;
  margin-bottom: 18px;
}

.math-code {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.95rem;
  color: var(--gold);
  background: rgba(232,197,71,0.08);
  padding: 3px 10px;
  border-radius: 6px;
  display: inline-block;
}

/* ── Layout ── */
.container-main {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem;
}

.section-block {
  padding: 5rem 0;
  border-bottom: 1px solid var(--section-border);
}
.section-block:last-of-type { border-bottom: none; }

.row {
  display: flex;
  gap: 2.5rem;
  align-items: flex-start;
}
.col-6 { flex: 1; }
.col-7 { flex: 1.4; }
.col-5 { flex: 0.8; }

@media (max-width: 768px) {
  .row { flex-direction: column; gap: 1.5rem; }
  h1 { font-size: 2rem; }
  h2 { font-size: 1.5rem; }
  .section-block { padding: 3rem 0; }
  .container-main { padding: 0 1rem; }
}

.center { text-align: center; }

/* ── Hero ── */
.hero-section {
  position: relative;
  min-height: 90vh;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  padding: 4rem 2rem;
}
#hero-canvas {
  position: absolute;
  inset: 0;
  width: 100%; height: 100%;
  pointer-events: none;
  z-index: 0;
  opacity: 0.7;
}
.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 900px;
}

.venue-badge {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  letter-spacing: 3px;
  color: var(--gold);
  border: 1px solid var(--gold-dim);
  padding: 6px 20px;
  border-radius: 30px;
  display: inline-block;
  margin-bottom: 24px;
}

.hero-content h1 span.blue { color: var(--blue); }
.hero-content h1 span.gold { color: var(--gold); }

.authors-line {
  margin-top: 28px;
  font-size: 1.1rem;
  color: var(--text-dim);
}
.authors-line a { color: var(--blue); font-weight: 500; }
.authors-line a:hover { color: var(--gold); }
.authors-line sup { font-size: 0.65em; color: var(--gold); }

.affiliations-line {
  margin-top: 6px;
  font-size: 0.85rem;
  color: var(--text-dim);
  opacity: 0.7;
  line-height: 1.8;
}
.equal-line {
  font-size: 0.75rem;
  color: var(--text-dim);
  opacity: 0.45;
  font-style: italic;
  margin-top: 4px;
}

/* ── Link buttons ── */
.link-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 2rem;
}
.link-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 30px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text);
  background: rgba(0,0,0,0.04);
  border: 1px solid rgba(0,0,0,0.12);
  transition: all 0.3s ease;
  text-decoration: none;
  letter-spacing: 0.5px;
}
.link-btn:hover {
  background: rgba(88,166,255,0.12);
  border-color: var(--blue);
  color: var(--blue);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(88,166,255,0.15);
}


/* ── Diagram containers ── */
.diagram {
  position: relative;
  border: 1px solid var(--card-border);
  border-radius: 16px;
  background: var(--diagram-bg);
  overflow: hidden;
  padding: 1.5rem;
}
.diagram svg,
.diagram img {
  width: 100%;
  height: auto;
  display: block;
}

/* ── Metric cards ── */
.metric-card {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 14px;
  padding: 20px 24px;
  margin-bottom: 14px;
  position: relative;
  overflow: hidden;
  transition: all 0.4s ease;
}
.metric-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}
.metric-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 3px; height: 100%;
  border-radius: 3px;
}
.metric-card.blue-b::before { background: var(--blue); }
.metric-card.gold-b::before { background: var(--gold); }
.metric-card.green-b::before { background: var(--green); }
.metric-card.red-b::before { background: var(--red); }
.metric-card.pink-b::before { background: var(--pink); }

.metric-card h4 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 6px;
}
.metric-card p {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-dim);
}
.metric-card p strong { color: var(--text); font-weight: 600; }

/* ── Callout ── */
.callout {
  padding: 16px 20px;
  border: 1px solid var(--callout-border);
  border-radius: 12px;
  background: var(--callout-bg);
  margin-top: 1.5rem;
}
.callout p { font-size: 1rem; color: var(--gold); }

/* ── SVG animations ── */
.traj-line {
  stroke-dasharray: 1000;
  stroke-dashoffset: 1000;
  transition: stroke-dashoffset 2s ease;
}
.is-visible .traj-line { stroke-dashoffset: 0; }

.dot-pulse { animation: none; }
.is-visible .dot-pulse { animation: pulse 1.5s ease infinite; }
@keyframes pulse {
  0%, 100% { r: 5; opacity: 0.6; }
  50% { r: 9; opacity: 1; }
}

/* ── Bar chart fills ── */
.bar-fill { transition: width 1.2s cubic-bezier(0.25,0.1,0.25,1); }
.fade-section:not(.is-visible) .bar-fill { width: 0 !important; }

/* ── Fade-in on scroll ── */
.fade-section {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}
.fade-section.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Stagger cards ── */
.stagger-card {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.stagger-card.is-visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Comparison grid ── */
.comparison-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}
@media (max-width: 768px) { .comparison-grid { grid-template-columns: 1fr; } }

/* ── Dataset grid ── */
.dataset-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}
@media (max-width: 768px) { .dataset-grid { grid-template-columns: 1fr; } }

/* ── Takeaway grid ── */
.takeaway-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.2rem;
}
@media (max-width: 768px) { .takeaway-grid { grid-template-columns: 1fr; } }

.takeaway-item {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 1.2rem 1.4rem;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  border-radius: 14px;
  transition: all 0.3s ease;
}
.takeaway-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-glow);
}
.takeaway-icon {
  width: 40px; height: 40px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem; font-weight: 700;
  flex-shrink: 0;
  border: 2px solid;
}
.takeaway-item p { font-size: 0.95rem; line-height: 1.7; }

/* ── Metric pills ── */
.metric-pill {
  display: inline-block;
  padding: 4px 14px;
  border-radius: 20px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.7rem;
  font-weight: 500;
  margin: 3px 4px;
  transition: transform 0.2s ease;
}
.metric-pill:hover { transform: translateY(-1px); }
.metric-pill.blue { background: rgba(88,166,255,0.1); color: var(--blue); border: 1px solid rgba(88,166,255,0.25); }
.metric-pill.gold { background: rgba(232,197,71,0.1); color: var(--gold); border: 1px solid rgba(232,197,71,0.25); }
.metric-pill.green { background: rgba(90,230,130,0.1); color: var(--green); border: 1px solid rgba(90,230,130,0.25); }
.metric-pill.red { background: rgba(255,107,122,0.1); color: var(--red); border: 1px solid rgba(255,107,122,0.25); }
.metric-pill.pink { background: rgba(224,122,255,0.1); color: var(--pink); border: 1px solid rgba(224,122,255,0.25); }

/* ── BibTeX ── */
.bibtex-section { position: relative; }
.bibtex-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}
.copy-btn {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.75rem;
  padding: 6px 16px;
  border-radius: 20px;
  border: 1px solid var(--card-border);
  background: var(--surface);
  color: var(--text-dim);
  cursor: pointer;
  transition: all 0.3s ease;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.copy-btn:hover {
  border-color: var(--gold);
  color: var(--gold);
  background: var(--callout-bg);
}
.copy-btn.copied { border-color: var(--green); color: var(--green); }

pre {
  background: var(--card-bg) !important;
  border: 1px solid var(--card-border) !important;
  border-radius: 14px !important;
  padding: 1.5rem !important;
  font-size: 0.85rem !important;
  overflow-x: auto;
  color: var(--text-dim) !important;
}
code {
  font-family: 'JetBrains Mono', monospace !important;
  background: transparent !important;
  color: var(--text-dim) !important;
}

/* ── Scroll to top ── */
.scroll-to-top {
  position: fixed;
  bottom: 2rem; right: 2rem;
  width: 44px; height: 44px;
  background: var(--surface);
  border: 1px solid var(--card-border);
  color: var(--text-dim);
  border-radius: 50%;
  cursor: pointer;
  opacity: 0; visibility: hidden;
  transition: all 0.3s ease;
  z-index: 999;
  display: flex; align-items: center; justify-content: center;
  font-size: 1rem;
  backdrop-filter: blur(8px);
}
.scroll-to-top:hover {
  border-color: var(--gold);
  color: var(--gold);
  background: var(--callout-bg);
}
.scroll-to-top.visible { opacity: 1; visibility: visible; }

/* ── Footer ── */
.footer-section {
  padding: 2.5rem 0;
  text-align: center;
  border-top: 1px solid var(--section-border);
}
.footer-section p {
  font-size: 0.85rem;
  color: var(--text-dim);
  opacity: 0.6;
}
.footer-section a { color: var(--blue); }
.footer-section a:hover { color: var(--gold); }

/* ── SVG text ── */
svg text { font-family: 'EB Garamond', serif; }