/* ---------- Design tokens ---------- */
:root {
  --bg: #f8f7f4;
  --bg-alt: #ffffff;
  --ink: #16181d;
  --ink-soft: #52555c;
  --ink-faint: #8a8d94;
  --line: #e7e5df;
  --accent: #0d7d72;
  --accent-ink: #ffffff;
  --accent-soft: #e4f3f1;
  --amber: #c2730a;
  --good: #1a8a4a;
  --bad: #c0392b;
  --card: #ffffff;
  --shadow: 0 1px 2px rgba(20, 20, 20, 0.04), 0 8px 24px rgba(20, 20, 20, 0.06);
  --radius: 14px;
  --radius-sm: 9px;
  --max: 1180px;
  --serif: "Source Serif 4", "Iowan Old Style", "Palatino Linotype", Georgia, serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", "SF Mono", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img, video { max-width: 100%; display: block; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 28px;
}

section { padding: 74px 0; }
.section-tight { padding: 48px 0; }
.alt { background: var(--bg-alt); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 12.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 10px;
}
.eyebrow::before {
  content: "";
  width: 18px;
  height: 2px;
  background: var(--accent);
  display: inline-block;
}

h1, h2, h3, h4 { font-family: var(--serif); font-weight: 600; margin: 0 0 0.5em; color: var(--ink); }

.section-head {
  max-width: 760px;
  margin: 0 auto 42px;
  text-align: center;
}
.section-head h2 { font-size: clamp(1.6rem, 2.6vw, 2.1rem); }
.section-head p { color: var(--ink-soft); font-size: 1.02rem; margin: 0; }

code, .mono { font-family: var(--mono); }

/* ---------- Top nav ---------- */
.topnav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(248, 247, 244, 0.86);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.topnav .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 58px;
}
.topnav .brand {
  font-family: var(--serif);
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--ink);
  letter-spacing: 0.01em;
}
.topnav .brand span { color: var(--accent); }
.topnav nav { display: flex; gap: 26px; }
.topnav nav a {
  color: var(--ink-soft);
  font-size: 0.92rem;
  font-weight: 500;
}
.topnav nav a:hover { color: var(--accent); text-decoration: none; }
.navtoggle { display: none; }

/* ---------- Hero ---------- */
.hero { padding: 72px 0 76px; text-align: center; }
.hero h1 {
  font-size: clamp(2rem, 4.2vw, 3.15rem);
  line-height: 1.15;
  max-width: 920px;
  margin: 0 auto 10px;
}
.hero h1 .full {
  display: block;
  font-family: var(--sans);
  font-weight: 500;
  font-size: 0.42em;
  color: var(--ink-soft);
  margin-top: 10px;
  letter-spacing: 0.002em;
}
.authors {
  margin: 26px auto 6px;
  font-size: 1.05rem;
  max-width: 760px;
}
.authors a { color: var(--ink); font-weight: 600; }
.authors a:hover { color: var(--accent); }
.authors .noaffil { color: var(--ink); font-weight: 600; }
.sup { font-size: 0.68em; position: relative; top: -0.55em; color: var(--accent); }
.affils { color: var(--ink-soft); font-size: 0.95rem; margin-bottom: 4px; }
.venue {
  display: inline-block;
  margin: 14px 0 26px;
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--amber);
  border: 1px solid #ecd4ab;
  background: #fdf5e8;
  padding: 6px 14px;
  border-radius: 999px;
}

.btnrow {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 54px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.92rem;
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--ink);
  box-shadow: var(--shadow);
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.btn:hover { transform: translateY(-1px); border-color: var(--accent); text-decoration: none; color: var(--accent); }
.btn.primary { background: var(--ink); color: #fff; border-color: var(--ink); }
.btn.primary:hover { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn svg { width: 16px; height: 16px; flex: none; }
.btn.disabled {
  color: var(--ink-faint);
  cursor: default;
  box-shadow: none;
}
.btn.disabled:hover { transform: none; border-color: var(--line); color: var(--ink-faint); text-decoration: none; }
.btn.disabled .soon {
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-faint);
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 2px 7px;
}

/* ---------- Pull quote / teaser line ---------- */
.lede {
  max-width: 820px;
  margin: 0 auto;
  text-align: center;
  font-family: var(--serif);
  font-size: 1.3rem;
  line-height: 1.55;
  color: var(--ink);
}
.lede em { color: var(--accent); font-style: normal; }

/* ---------- Video pair card ---------- */
.pair-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 22px;
  text-align: left;
  max-width: var(--max);
  margin: 0 auto;
}
.pair-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
}
.pair-prompt {
  font-family: var(--serif);
  font-style: italic;
  font-size: 0.97rem;
  color: var(--ink);
  margin-bottom: 4px;
  min-height: 2.6em;
}
.pair-physics {
  font-size: 0.78rem;
  color: var(--accent);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  margin-bottom: 12px;
}
.pair-videos { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
.vcell { display: flex; flex-direction: column; gap: 6px; }
.vcell h4 {
  font-family: var(--sans);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0;
  text-align: center;
}
.vcell.is-ours h4 { color: var(--accent); }
.vframe { position: relative; border-radius: var(--radius-sm); overflow: hidden; background: #0d0f12; aspect-ratio: 16/9; }
.vframe video { width: 100%; height: 100%; object-fit: cover; }
.tags { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 8px; }
.tag {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 4px 9px 4px 7px;
  border-radius: 999px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}
.tag.bad { background: #fbeae8; color: var(--bad); }
.tag.good { background: #e7f6ec; color: var(--good); }

/* ---------- Method ---------- */
.method-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
}
.method-copy h3 { font-size: 1.2rem; margin-top: 1.1em; }
.method-copy p { color: var(--ink-soft); }
.failure-list { list-style: none; margin: 18px 0; padding: 0; display: grid; gap: 12px; }
.failure-list li {
  display: flex;
  gap: 12px;
  background: var(--bg-alt);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
}
.failure-list .dot {
  flex: none;
  width: 26px; height: 26px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--serif); font-weight: 700; font-size: 0.85rem;
}
.failure-list b { color: var(--ink); }
.failure-list span { color: var(--ink-soft); font-size: 0.93rem; }

.diagram-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  box-shadow: var(--shadow);
}
.diagram-card img { width: 100%; }
.diagram-caption { font-size: 0.85rem; color: var(--ink-faint); margin-top: 12px; }

.stat-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: 46px;
}
.stat {
  text-align: center;
  background: var(--bg-alt);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 14px;
}
.stat .num { font-family: var(--serif); font-size: 2rem; color: var(--accent); font-weight: 700; }
.stat .lbl { font-size: 0.85rem; color: var(--ink-soft); margin-top: 4px; }

/* ---------- Comparison rows (multi-method) ---------- */
.compare-row {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
  margin-bottom: 22px;
}
.compare-row .pair-prompt { min-height: auto; margin-bottom: 2px; }
.compare-row .pair-physics { margin-bottom: 14px; }
.compare-5 { display: grid; grid-template-columns: repeat(5, 1fr); gap: 10px; }

/* ---------- Simple two-up grid (ours vs wan) ---------- */
.duo-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

/* ---------- Backbone ablation ---------- */
.backbone-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
.backbone-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}
.backbone-card .badge {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 10px;
}

/* ---------- Toggle / show more ---------- */
.more-wrap { text-align: center; margin-top: 30px; }
.more-panel { display: none; margin-top: 26px; }
.more-panel.open { display: block; }
.btn.ghost { background: transparent; box-shadow: none; }

/* ---------- BibTeX ---------- */
.bibtex-box {
  position: relative;
  background: #11131a;
  color: #d6e4d9;
  border-radius: var(--radius);
  padding: 24px 24px;
  font-family: var(--mono);
  font-size: 0.84rem;
  line-height: 1.65;
  overflow-x: auto;
  box-shadow: var(--shadow);
}
.bibtex-box #bibtex-text {
  white-space: pre;
  margin: 0;
}
.bibtex-box .copy-btn {
  position: absolute;
  top: 14px; right: 14px;
  background: rgba(255,255,255,0.08);
  color: #d6e4d9;
  border: 1px solid rgba(255,255,255,0.15);
  border-radius: 7px;
  font-family: var(--sans);
  font-size: 0.75rem;
  padding: 6px 10px;
  cursor: pointer;
}
.bibtex-box .copy-btn:hover { background: rgba(255,255,255,0.16); }
.bib-kw { color: #7fc8a9; }
.bib-key { color: #e3b05c; }
.bib-field { color: #9aa3b2; }
.bib-val { color: #cfe3d4; }

/* ---------- Footer ---------- */
footer {
  padding: 40px 0 60px;
  text-align: center;
  color: var(--ink-faint);
  font-size: 0.85rem;
}
footer a { color: var(--ink-soft); }

/* ---------- Responsive ---------- */
@media (max-width: 920px) {
  .pair-grid { grid-template-columns: 1fr; }
  .method-grid { grid-template-columns: 1fr; }
  .stat-row { grid-template-columns: 1fr; }
  .compare-5 { grid-template-columns: repeat(2, 1fr); }
  .duo-grid { grid-template-columns: 1fr; }
  .backbone-grid { grid-template-columns: 1fr; }
  .topnav nav { display: none; }
}