:root {
  --primary: #2c6fbb;
  --primary-dark: #1f4f87;
  --accent: #c8553d;
  --bg: #ffffff;
  --bg-alt: #f7f8fa;
  --text: #222;
  --text-light: #666;
  --border: #e2e5ea;
  --radius: 10px;
  --max-width: 980px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  font-size: 16px;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

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

/* Navbar */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  justify-content: center;
  align-items: center;
}
.nav-title { font-weight: 700; color: var(--primary-dark); font-size: 15px; }
.nav-links { display: flex; gap: 24px; justify-content: center; }
.nav-links a { font-size: 14px; color: var(--text-light); }
.nav-links a:hover { color: var(--primary); text-decoration: none; }
.nav-links a:hover { color: var(--primary); text-decoration: none; }

/* Hero */
.hero {
  text-align: center;
  padding: 70px 24px 50px;
  background: linear-gradient(180deg, #f0f5fb 0%, #ffffff 100%);
}
.hero .tag {
  text-transform: uppercase;
  letter-spacing: 1.5px;
  font-size: 12px;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 18px;
}
.hero h1 {
  font-size: 32px;
  line-height: 1.3;
  max-width: 820px;
  margin: 0 auto 28px;
  color: var(--text);
}
.authors {
  font-size: 16px;
  margin-bottom: 10px;
}
.authors a { font-weight: 600; }
.author-plain { color: var(--text); }
.affils {
  font-size: 13px;
  color: var(--text-light);
  margin-bottom: 4px;
}
.buttons { margin-bottom: 44px; }
.btn {
  display: inline-block;
  padding: 11px 26px;
  border-radius: 30px;
  font-weight: 600;
  font-size: 15px;
  margin: 0 8px;
  transition: transform 0.15s, box-shadow 0.15s;
}
.btn:hover { text-decoration: none; transform: translateY(-2px); }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); color: #fff; box-shadow: 0 4px 12px rgba(44,111,187,0.3); }
.btn-secondary { background: #fff; color: var(--primary-dark); border: 1.5px solid var(--primary); }
.btn-secondary:hover { background: var(--primary); color: #fff; }

.stats {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 14px;
  max-width: 920px;
  margin: 0 auto;
}
.stat {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 16px;
  flex: 0 1 calc(20% - 14px);
  min-width: 132px;
  text-align: center;
  transition: box-shadow 0.2s, transform 0.2s;
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}
.stat:hover { box-shadow: 0 4px 14px rgba(0,0,0,0.08); transform: translateY(-2px); }
.stat-num {
  font-size: 34px;
  font-weight: 700;
  color: var(--primary-dark);
  line-height: 1;
}
.stat-label {
  font-size: 13px;
  color: var(--text-light);
  margin-top: 8px;
  line-height: 1.3;
}

/* Sections */
.section { padding: 60px 0; }
.section-alt { background: var(--bg-alt); }
.section h2 {
  font-size: 28px;
  margin-bottom: 24px;
  text-align: center;
  color: var(--text);
}
.section-intro {
  max-width: 760px;
  margin: 0 auto 36px;
  text-align: center;
  color: var(--text-light);
}

/* Abstract */
.abstract-text {
  max-width: 820px;
  margin: 0 auto 32px;
  text-align: justify;
}
.figure-teaser {
  max-width: 880px;
  margin: 0 auto;
}
.figure-teaser img { width: 100%; border-radius: var(--radius); border: 1px solid var(--border); }
.figure-teaser figcaption {
  font-size: 14px;
  color: var(--text-light);
  text-align: center;
  margin-top: 12px;
  font-style: italic;
}

/* Cards */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}
.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: box-shadow 0.2s, transform 0.2s;
}
.card:hover { box-shadow: 0 6px 20px rgba(0,0,0,0.08); transform: translateY(-3px); }
.card-label {
  font-size: 11px;
  letter-spacing: 1.5px;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 10px;
}
.card h3 {
  font-size: 18px;
  margin-bottom: 12px;
  color: var(--primary-dark);
}
.card p { font-size: 14.5px; color: var(--text-light); }

.cards-prior {
  margin-top: 36px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  align-items: stretch;
}
.cards-prior .card {
  display: flex;
  flex-direction: column;
  height: 100%;
}
.cards-prior .card p {
  flex: 1 1 auto;
}
.cards-prior .card img {
  width: 100%;
  height: 220px;
  object-fit: contain;
  object-position: center bottom;
  background: #fafbfc;
  border-radius: 6px;
  margin-top: 16px;
  border: 1px solid var(--border);
  display: block;
}
.card-geo { border-top: 4px solid #3b82f6; }
.card-sem { border-top: 4px solid #10b981; }
.card-vis { border-top: 4px solid #f59e0b; }

@media (max-width: 900px) {
  .cards-prior {
    grid-template-columns: 1fr;
  }
  .cards-prior .card img {
    height: 240px;
  }
}

/* Main figures */
.figure-main {
  max-width: 820px;
  margin: 36px auto;
}
.figure-main img { width: 100%; border-radius: var(--radius); border: 1px solid var(--border); }
.figure-main figcaption {
  font-size: 14px;
  color: var(--text-light);
  text-align: center;
  margin-top: 12px;
  font-style: italic;
}

/* Prior–Task combinations */
.combo-legend {
  display: flex;
  justify-content: center;
  gap: 28px;
  margin: 0 auto 18px;
  font-size: 13px;
  color: var(--text-light);
}
.combo-legend .dot {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  margin-right: 6px;
  vertical-align: middle;
}
.combo-legend .dot.filled { background: var(--primary); }
.combo-legend .dot.empty {
  background: transparent;
  border: 1.5px solid #c5cbd3;
}
.table-wrap {
  overflow-x: auto;
  margin: 0 auto 28px;
  max-width: 920px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: #fff;
}
.combo-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13.5px;
  min-width: 720px;
}
.combo-table th,
.combo-table td {
  padding: 12px 10px;
  border-bottom: 1px solid var(--border);
  text-align: center;
}
.combo-table th {
  background: #f3f6fa;
  color: var(--primary-dark);
  font-weight: 700;
  font-size: 12.5px;
}
.combo-table td:first-child,
.combo-table th:first-child {
  text-align: left;
  padding-left: 16px;
  font-weight: 600;
  color: var(--text);
}
.combo-table td:nth-child(2),
.combo-table th:nth-child(2) {
  text-align: left;
}
.combo-table tbody tr:last-child td { border-bottom: none; }
.combo-table tbody tr:hover { background: #fafbfd; }
.cell-yes {
  color: var(--primary-dark);
  font-size: 18px;
  font-weight: 700;
}
.cell-empty { color: #c5cbd3; }
.pill {
  display: inline-block;
  padding: 3px 8px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.3px;
}
.pill-geo { background: #e8f1ff; color: #2563eb; }
.pill-sem { background: #e9fbf3; color: #059669; }
.pill-vis { background: #fff7e6; color: #d97706; }

.combo-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 12px;
  max-width: 920px;
  margin: 0 auto;
}
.combo-chip {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 12px 14px;
  font-size: 13.5px;
  color: var(--text);
  box-shadow: 0 1px 2px rgba(0,0,0,0.03);
}
.chip-tag {
  display: inline-block;
  min-width: 52px;
  margin-right: 8px;
  padding: 2px 7px;
  border-radius: 5px;
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.3px;
  text-align: center;
}
.chip-tag.geo { background: #e8f1ff; color: #2563eb; }
.chip-tag.sem { background: #e9fbf3; color: #059669; }
.chip-tag.vis { background: #fff7e6; color: #d97706; }

/* Challenges */
.challenges {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.challenge {
  display: flex;
  gap: 18px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
}
.challenge-num {
  font-size: 32px;
  font-weight: 800;
  color: var(--primary);
  opacity: 0.35;
  line-height: 1;
  min-width: 44px;
}
.challenge-body h3 { font-size: 16px; margin-bottom: 8px; color: var(--primary-dark); }
.challenge-body p { font-size: 14px; color: var(--text-light); }

/* BibTeX */
.bibtex-wrap {
  position: relative;
  max-width: 680px;
  margin: 0 auto;
}
.bibtex-wrap pre {
  background: #1e2530;
  color: #e6e6e6;
  padding: 24px;
  border-radius: var(--radius);
  font-size: 13.5px;
  overflow-x: auto;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}
.copy-btn {
  position: absolute;
  top: 12px;
  right: 12px;
  background: #3a4452;
  color: #fff;
  border: none;
  padding: 6px 14px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
}
.copy-btn:hover { background: var(--primary); }

/* Footer */
footer {
  background: #1e2530;
  color: #b8c2cc;
  padding: 36px 0;
  text-align: center;
}
.footer-links { margin-bottom: 10px; }
.footer-links a { color: #fff; margin: 0 12px; font-size: 14px; }
.footer-credit { font-size: 12px; color: #7a8694; }

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 24px; }
  .stats { gap: 24px; }
  .stat-num { font-size: 26px; }
  .nav-links { display: none; }
  .challenges { grid-template-columns: 1fr; }
}