/* =================================================================
   AVP project page — DreamBooth/Imagen-inspired dark theme
   ================================================================= */

:root {
  --bg:           #0a0d14;
  --bg-elev:      #11151f;
  --card:         rgba(255, 255, 255, 0.04);
  --card-border:  rgba(255, 255, 255, 0.08);
  --text:         #e8ecf3;
  --text-dim:     #99a2b3;
  --text-faint:   #5d6678;
  --accent:       #ff8b3d;      /* warm orange */
  --accent-2:     #5aa9ff;      /* cool blue   */
  --accent-3:     #b885ff;      /* purple      */
  --grad: linear-gradient(135deg, #ff8b3d 0%, #b885ff 40%, #5aa9ff 100%);
  --radius:       14px;
  --shadow:       0 10px 40px -10px rgba(0, 0, 0, 0.6);
  --max:          1180px;
  --max-narrow:   840px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 72px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif;
  font-size: 16px;
  line-height: 1.62;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

a { color: var(--accent-2); text-decoration: none; transition: opacity 0.2s; }
a:hover { opacity: 0.8; }

.mono { font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: 0.92em; }

/* =================================================================
   Animated background
   ================================================================= */
.bg-gradient {
  position: fixed; inset: 0; z-index: -2;
  background:
    radial-gradient(ellipse 60% 50% at 20% 0%, rgba(255, 139, 61, 0.18), transparent 60%),
    radial-gradient(ellipse 60% 50% at 80% 30%, rgba(184, 133, 255, 0.14), transparent 65%),
    radial-gradient(ellipse 80% 60% at 50% 100%, rgba(90, 169, 255, 0.10), transparent 60%);
  animation: shift 30s ease-in-out infinite alternate;
}
@keyframes shift {
  0%   { transform: scale(1)   translate(0,0);    }
  100% { transform: scale(1.1) translate(2%, -2%); }
}

.bg-grain {
  position: fixed; inset: 0; z-index: -1; opacity: 0.025; pointer-events: none;
  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='180' height='180'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2'/><feColorMatrix values='0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0.5 0'/></filter><rect width='180' height='180' filter='url(%23n)'/></svg>");
}

/* =================================================================
   Nav
   ================================================================= */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 50;
  backdrop-filter: blur(14px);
  background: rgba(10, 13, 20, 0.6);
  border-bottom: 1px solid var(--card-border);
}
.nav-inner {
  max-width: var(--max); margin: 0 auto;
  padding: 14px 28px;
  display: flex; align-items: center; justify-content: space-between;
}
.nav-brand {
  font-weight: 800; font-size: 18px; letter-spacing: 0.04em;
  color: var(--text);
  background: var(--grad); -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.nav-links { display: flex; gap: 26px; font-size: 14px; }
.nav-links a { color: var(--text-dim); }
.nav-links a:hover { color: var(--text); opacity: 1; }
@media (max-width: 640px) {
  .nav-links { gap: 14px; font-size: 12px; }
}

/* =================================================================
   Hero
   ================================================================= */
.hero {
  padding: 140px 28px 90px;
  text-align: center;
}
.hero-inner { max-width: var(--max); margin: 0 auto; }

.eyebrow {
  display: inline-block;
  font-size: 12px; letter-spacing: 0.22em; font-weight: 600;
  text-transform: uppercase;
  color: var(--text-faint);
  padding: 4px 12px;
  border: 1px solid var(--card-border);
  border-radius: 100px;
  margin-bottom: 28px;
}
.eyebrow.center { display: block; max-width: max-content; margin: 0 auto 16px; }

.hero-title {
  font-size: clamp(40px, 6.5vw, 80px);
  line-height: 1.05;
  font-weight: 800;
  letter-spacing: -0.025em;
  margin: 0 0 22px;
}
.grad {
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
  animation: hue 12s ease-in-out infinite;
}
@keyframes hue { 0%,100% { filter: hue-rotate(0deg);} 50% { filter: hue-rotate(15deg);} }

.hero-tagline {
  max-width: 760px; margin: 0 auto 36px;
  font-size: clamp(16px, 1.6vw, 19px);
  color: var(--text-dim);
}
.hl { color: var(--text); font-weight: 600; }

.authors {
  display: flex; flex-wrap: wrap; justify-content: center;
  gap: 12px 22px; max-width: 920px; margin: 0 auto 14px;
  font-size: 15px;
}
.author a { color: var(--text); font-weight: 500; }
.author sup { color: var(--accent); font-weight: 700; font-size: 11px; }

.affil {
  color: var(--text-dim); font-size: 14px;
  display: flex; justify-content: center; flex-wrap: wrap; gap: 6px 12px;
  margin-top: 10px;
}
.affil.legend { color: var(--text-faint); font-size: 12px; margin-top: 4px; }
.affil sup { color: var(--accent); font-weight: 700; }
.affil .sep { color: var(--text-faint); }

.cta {
  display: flex; justify-content: center; gap: 12px; flex-wrap: wrap;
  margin-top: 36px;
}
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 11px 22px;
  border: 1px solid var(--card-border);
  border-radius: 100px;
  background: var(--card);
  color: var(--text);
  font-size: 14px; font-weight: 500;
  transition: transform 0.2s, background 0.2s, border-color 0.2s;
}
.btn:hover {
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.07);
  border-color: rgba(255, 255, 255, 0.18);
  opacity: 1;
}
.btn-primary {
  background: var(--grad);
  border: none;
  color: white;
  box-shadow: 0 8px 30px -8px rgba(255, 139, 61, 0.5);
}
.btn-primary:hover { color: white; }

/* =================================================================
   Sections
   ================================================================= */
.section { padding: 90px 28px; }
.container { max-width: var(--max); margin: 0 auto; }
.container.narrow { max-width: var(--max-narrow); }

.section-title {
  font-size: clamp(28px, 3.5vw, 42px);
  font-weight: 700;
  letter-spacing: -0.02em;
  text-align: center;
  margin: 0 0 18px;
}
.section-title em { color: var(--accent); font-style: normal; }
.section-lead {
  max-width: 780px; margin: 0 auto 48px;
  text-align: center; color: var(--text-dim);
  font-size: 17px;
}

.card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  padding: 28px 32px;
  backdrop-filter: blur(8px);
}

.abstract-card {
  padding: 36px 40px;
  font-size: 16px;
}
.abstract-card p { margin: 0 0 14px; }
.abstract-card p:last-child { margin: 0; }
.abstract-card b { color: var(--text); }
.abstract-card em { color: var(--accent); font-style: normal; }

/* =================================================================
   Figures
   ================================================================= */
.figure {
  margin: 0 0 36px;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--card);
  border: 1px solid var(--card-border);
  box-shadow: var(--shadow);
}
.figure img {
  display: block; width: 100%; height: auto;
}
.figure figcaption {
  padding: 18px 24px;
  font-size: 14px;
  color: var(--text-dim);
  border-top: 1px solid var(--card-border);
}

/* =================================================================
   Grid
   ================================================================= */
.grid { display: grid; gap: 18px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 980px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 600px) {
  .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

/* Primitive taxonomy cards */
.primitive-card { position: relative; padding: 24px; }
.primitive-card .ptag {
  position: absolute; top: 18px; right: 18px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 12px; color: var(--accent); font-weight: 600;
  letter-spacing: 0.04em;
}
.primitive-card h3 {
  margin: 4px 0 10px;
  font-size: 17px; font-weight: 700;
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text; -webkit-text-fill-color: transparent;
}
.primitive-card p {
  margin: 0; font-size: 14px; color: var(--text-dim);
}

/* =================================================================
   Video grid
   ================================================================= */
/* Center the last row when 5 items in a 3-col grid */
.video-grid { justify-content: center; }

.video-card {
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.3s, border-color 0.3s;
}
.video-card:hover { transform: translateY(-4px); border-color: rgba(255, 255, 255, 0.18); }

.video-thumb {
  position: relative;
  aspect-ratio: 16 / 10;
  background:
    linear-gradient(135deg, #1a2030 0%, #0d1019 100%);
  display: flex; align-items: center; justify-content: center;
  overflow: hidden;
}
.video-card video,
.video-card img { display: block; width: 100%; height: 100%; object-fit: cover; }

.video-card .badge {
  position: absolute; top: 12px; left: 12px;
  font-size: 11px; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase;
  color: var(--text);
  padding: 4px 10px;
  background: rgba(0, 0, 0, 0.55);
  border: 1px solid var(--card-border);
  border-radius: 100px;
  backdrop-filter: blur(6px);
}

.video-card .play {
  width: 54px; height: 54px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.15);
  position: relative;
  transition: transform 0.3s, background 0.3s;
}
.video-card .play::after {
  content: ''; position: absolute;
  top: 50%; left: 56%; transform: translate(-50%, -50%);
  border-left: 14px solid var(--text);
  border-top: 9px solid transparent;
  border-bottom: 9px solid transparent;
  opacity: 0.85;
}
.video-card:hover .play { transform: scale(1.1); background: rgba(255, 255, 255, 0.14); }

.video-card .coming {
  position: absolute; bottom: 12px; right: 12px;
  font-size: 11px; color: var(--text-faint);
  font-style: italic;
}
.video-card.placeholder .video-thumb {
  background:
    radial-gradient(circle at 30% 30%, rgba(255, 139, 61, 0.10), transparent 60%),
    radial-gradient(circle at 70% 70%, rgba(90, 169, 255, 0.08), transparent 60%),
    linear-gradient(135deg, #1a2030 0%, #0d1019 100%);
}

.video-card h4 {
  margin: 16px 20px 6px;
  font-size: 15px; font-weight: 600;
}
.video-card p {
  margin: 0 20px 18px;
  font-size: 13px; color: var(--text-dim);
}

/* =================================================================
   BibTeX
   ================================================================= */
.bibtex {
  position: relative;
  background: var(--bg-elev);
  border: 1px solid var(--card-border);
  border-radius: var(--radius);
  overflow: hidden;
}
.bibtex pre {
  margin: 0; padding: 22px 24px;
  overflow-x: auto;
  font-family: 'JetBrains Mono', monospace;
  font-size: 13px; line-height: 1.65;
  color: var(--text);
}
.copy-btn {
  position: absolute; top: 12px; right: 12px;
  padding: 6px 14px;
  background: var(--card);
  border: 1px solid var(--card-border);
  color: var(--text-dim);
  border-radius: 100px;
  font-size: 12px; font-weight: 500;
  cursor: pointer;
  transition: background 0.2s, color 0.2s;
}
.copy-btn:hover { color: var(--text); background: rgba(255, 255, 255, 0.07); }
.copy-btn.copied { color: var(--accent); }

/* =================================================================
   Footer
   ================================================================= */
.footer {
  padding: 60px 28px 80px;
  text-align: center;
  color: var(--text-dim);
  font-size: 13px;
  border-top: 1px solid var(--card-border);
  margin-top: 60px;
}
.footer .muted { color: var(--text-faint); font-size: 12px; margin-top: 8px; }
.footer a { color: var(--accent-2); }

/* =================================================================
   Scroll-triggered reveal
   ================================================================= */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.8s cubic-bezier(0.2, 0.7, 0.2, 1),
              transform 0.8s cubic-bezier(0.2, 0.7, 0.2, 1);
}
.reveal.in-view { opacity: 1; transform: translateY(0); }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .bg-gradient { animation: none; }
  .grad { animation: none; }
}