@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500&display=swap');

:root {
  --navy: #1a1a2e;
  --navy-light: #16213e;
  --teal: #16697a;
  --teal-light: #489fb5;
  --coral: #db6400;
  --coral-light: #e8852a;
  --bg: #f8f9fa;
  --bg-card: #ffffff;
  --text: #2d3436;
  --text-light: #636e72;
  --text-muted: #b2bec3;
  --border: #dfe6e9;
  --shadow: 0 2px 8px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
  --radius: 8px;
  --radius-lg: 12px;
  --max-width: 1200px;
  --header-height: 64px;
  --sidebar-width: 260px;
  --transition: all 0.3s ease;
}

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

html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-height) + 20px); }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

/* ===== HEADER / NAV ===== */
.header {
  position: sticky; top: 0; z-index: 1000;
  background: var(--navy);
  box-shadow: 0 2px 20px rgba(0,0,0,0.3);
}
.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  height: var(--header-height);
}
.logo {
  font-weight: 800;
  font-size: 1.1rem;
  color: #fff;
  text-decoration: none;
  letter-spacing: -0.5px;
}
.logo span { color: var(--teal-light); }

.nav-toggle { display: none; }
.nav-toggle-label {
  display: none;
  cursor: pointer;
  padding: 10px;
}
.nav-toggle-label span,
.nav-toggle-label span::before,
.nav-toggle-label span::after {
  display: block;
  background: #fff;
  height: 2px;
  width: 24px;
  border-radius: 2px;
  position: relative;
  transition: var(--transition);
}
.nav-toggle-label span::before,
.nav-toggle-label span::after {
  content: '';
  position: absolute;
}
.nav-toggle-label span::before { top: -7px; }
.nav-toggle-label span::after { top: 7px; }

.nav-links {
  display: flex;
  list-style: none;
  gap: 4px;
}
.nav-links a {
  color: rgba(255,255,255,0.75);
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 500;
  padding: 8px 12px;
  border-radius: 6px;
  transition: var(--transition);
  white-space: nowrap;
}
.nav-links a:hover, .nav-links a.active {
  color: #fff;
  background: rgba(255,255,255,0.1);
}
.nav-links a.active { background: var(--teal); }

@media (max-width: 900px) {
  .nav-toggle-label { display: block; }
  .nav-links {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0; right: 0;
    flex-direction: column;
    background: var(--navy);
    padding: 12px 24px;
    box-shadow: var(--shadow-lg);
  }
  .nav-toggle:checked ~ .nav-links { display: flex; }
}

/* ===== HERO ===== */
.hero {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 40%, var(--teal) 100%);
  color: #fff;
  padding: 80px 24px 60px;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute;
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(22,105,122,0.3) 0%, transparent 70%);
  top: -200px; right: -100px;
  border-radius: 50%;
}
.hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 800;
  margin-bottom: 16px;
  line-height: 1.2;
  position: relative;
}
.hero .subtitle {
  font-size: 1.1rem;
  color: rgba(255,255,255,0.85);
  max-width: 700px;
  margin: 0 auto 24px;
  font-weight: 300;
  position: relative;
}
.hero .authors {
  font-size: 0.95rem;
  color: rgba(255,255,255,0.7);
  margin-bottom: 24px;
  position: relative;
}
.hero .authors strong { color: #fff; font-weight: 600; }
.btn-group { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; position: relative; }
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 20px;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: var(--transition);
}
.btn-primary { background: var(--coral); color: #fff; }
.btn-primary:hover { background: var(--coral-light); transform: translateY(-2px); }
.btn-outline { background: rgba(255,255,255,0.1); color: #fff; border: 1px solid rgba(255,255,255,0.3); }
.btn-outline:hover { background: rgba(255,255,255,0.2); transform: translateY(-2px); }

/* ===== LAYOUT ===== */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }
.page-layout {
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr;
  gap: 40px;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 40px 24px;
}
@media (max-width: 900px) {
  .page-layout { grid-template-columns: 1fr; }
  .sidebar { display: none; }
}

/* ===== SIDEBAR TOC ===== */
.sidebar {
  position: sticky;
  top: calc(var(--header-height) + 24px);
  align-self: start;
  max-height: calc(100vh - var(--header-height) - 48px);
  overflow-y: auto;
}
.toc {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  padding: 20px;
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.toc h3 {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-muted);
  margin-bottom: 12px;
  font-weight: 700;
}
.toc ul { list-style: none; }
.toc li { margin-bottom: 2px; }
.toc a {
  display: block;
  padding: 6px 12px;
  font-size: 0.85rem;
  color: var(--text-light);
  text-decoration: none;
  border-radius: 4px;
  border-left: 3px solid transparent;
  transition: var(--transition);
}
.toc a:hover { color: var(--teal); background: rgba(22,105,122,0.05); border-left-color: var(--teal-light); }
.toc a.active { color: var(--teal); background: rgba(22,105,122,0.08); border-left-color: var(--teal); font-weight: 600; }

/* ===== SECTIONS ===== */
.section { padding: 48px 0; }
.section-alt { background: #fff; }
.section-header {
  margin-bottom: 32px;
  padding-bottom: 16px;
  border-bottom: 2px solid var(--border);
}
.section-header h2 {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--navy);
  margin-bottom: 8px;
}
.section-header p { color: var(--text-light); font-size: 1rem; }

h2.accent-border {
  padding-left: 16px;
  border-left: 4px solid var(--teal);
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--navy);
  margin: 40px 0 20px;
}
h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--navy-light);
  margin: 32px 0 16px;
}
p { margin-bottom: 16px; }

/* ===== PAPER CARDS ===== */
.paper-grid { display: grid; grid-template-columns: 1fr; gap: 16px; margin: 24px 0; }
.paper-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: var(--transition);
  position: relative;
}
.paper-card:hover {
  border-color: var(--teal-light);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}
.paper-card .paper-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 4px;
  line-height: 1.4;
}
.paper-card .paper-title a {
  color: var(--navy);
  text-decoration: none;
}
.paper-card .paper-title a:hover { color: var(--teal); }
.paper-card .paper-meta {
  font-size: 0.82rem;
  color: var(--text-light);
  margin-bottom: 8px;
}
.paper-card .paper-desc {
  font-size: 0.9rem;
  color: var(--text);
  margin-bottom: 10px;
  line-height: 1.6;
}
.paper-card .paper-tags { display: flex; flex-wrap: wrap; gap: 6px; }

/* ===== BADGES ===== */
.badge {
  display: inline-block;
  padding: 2px 10px;
  border-radius: 20px;
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.3px;
  text-transform: uppercase;
}
.badge-self { background: #e8f5e9; color: #2e7d32; }
.badge-hybrid { background: #fff3e0; color: #e65100; }
.badge-auxiliary { background: #e3f2fd; color: #1565c0; }
.badge-ext { background: #f3e5f5; color: #7b1fa2; }
.badge-mech { background: #fce4ec; color: #c62828; }
.badge-peer { background: #e0f2f1; color: #00695c; }
.badge-unit { background: #eceff1; color: #37474f; }
.badge-role { background: #ede7f6; color: #4527a0; }
.badge-access { background: #e8eaf6; color: #283593; }
.badge-venue { background: var(--navy); color: #fff; }

/* ===== TAXONOMY CARDS ===== */
.taxonomy-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin: 32px 0;
}
.taxonomy-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: var(--transition);
  text-decoration: none;
  color: inherit;
  display: block;
  border-top: 4px solid var(--teal);
}
.taxonomy-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-top-color: var(--coral);
}
.taxonomy-card h3 {
  font-size: 1.1rem;
  color: var(--navy);
  margin: 0 0 8px;
}
.taxonomy-card .section-num {
  font-size: 0.8rem;
  color: var(--teal);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 4px;
}
.taxonomy-card p { font-size: 0.9rem; color: var(--text-light); margin: 0; }

/* ===== TABLES ===== */
.table-container {
  overflow-x: auto;
  margin: 24px 0;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  background: var(--bg-card);
}
thead {
  background: var(--navy);
  color: #fff;
  position: sticky;
  top: 0;
}
th {
  padding: 12px 16px;
  text-align: left;
  font-weight: 600;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  white-space: nowrap;
}
td {
  padding: 10px 16px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
tbody tr:nth-child(even) { background: rgba(0,0,0,0.02); }
tbody tr:hover { background: rgba(22,105,122,0.04); }
.table-group-header td {
  background: rgba(22,105,122,0.08);
  font-weight: 700;
  color: var(--navy);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

/* ===== FIGURE ===== */
.figure {
  margin: 32px 0;
  text-align: center;
}
.figure img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}
.figure figcaption {
  margin-top: 12px;
  font-size: 0.88rem;
  color: var(--text-light);
  font-style: italic;
}

/* ===== CALLOUT / NOTE ===== */
.callout {
  background: rgba(22,105,122,0.06);
  border-left: 4px solid var(--teal);
  padding: 16px 20px;
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 24px 0;
  font-size: 0.92rem;
}
.callout-warning {
  background: rgba(219,100,0,0.06);
  border-left-color: var(--coral);
}

/* ===== CHALLENGE CARDS ===== */
.challenge-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin: 20px 0;
  border-left: 5px solid var(--teal);
}
.challenge-card h3 {
  color: var(--navy);
  margin: 0 0 12px;
  font-size: 1.15rem;
}
.challenge-card.ch1 { border-left-color: #e74c3c; }
.challenge-card.ch2 { border-left-color: #f39c12; }
.challenge-card.ch3 { border-left-color: #3498db; }
.challenge-card.ch4 { border-left-color: #9b59b6; }
.challenge-card.ch5 { border-left-color: #1abc9c; }

/* ===== BIBTEX ===== */
.bibtex-block {
  background: var(--navy);
  color: #a8e6cf;
  padding: 20px 24px;
  border-radius: var(--radius);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  overflow-x: auto;
  position: relative;
  line-height: 1.6;
  white-space: pre;
}
.copy-btn {
  position: absolute;
  top: 12px; right: 12px;
  background: rgba(255,255,255,0.1);
  color: #fff;
  border: none;
  padding: 6px 14px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 0.78rem;
  font-weight: 600;
  transition: var(--transition);
}
.copy-btn:hover { background: rgba(255,255,255,0.2); }

/* ===== FOOTER ===== */
.footer {
  background: var(--navy);
  color: rgba(255,255,255,0.7);
  padding: 40px 24px 24px;
  margin-top: 60px;
  border-top: 3px solid var(--teal);
}
.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 32px;
}
.footer h4 {
  color: #fff;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 12px;
}
.footer a {
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  font-size: 0.85rem;
  transition: var(--transition);
}
.footer a:hover { color: var(--teal-light); }
.footer ul { list-style: none; }
.footer li { margin-bottom: 6px; }
.footer-bottom {
  max-width: var(--max-width);
  margin: 24px auto 0;
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,0.1);
  text-align: center;
  font-size: 0.82rem;
}

/* ===== CONTRIBUTIONS GRID ===== */
.contrib-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin: 24px 0;
}
.contrib-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
}
.contrib-item .num {
  font-size: 2rem;
  font-weight: 800;
  color: var(--teal);
  display: block;
  margin-bottom: 4px;
}
.contrib-item h4 { font-size: 0.95rem; margin-bottom: 6px; color: var(--navy); }
.contrib-item p { font-size: 0.85rem; color: var(--text-light); margin: 0; }

/* ===== PAGE HERO (section pages) ===== */
.page-hero {
  background: linear-gradient(135deg, var(--navy) 0%, var(--teal) 100%);
  color: #fff;
  padding: 48px 24px 36px;
}
.page-hero h1 {
  font-size: clamp(1.5rem, 3vw, 2.2rem);
  font-weight: 800;
  max-width: var(--max-width);
  margin: 0 auto 8px;
}
.page-hero p {
  max-width: var(--max-width);
  margin: 0 auto;
  font-size: 1rem;
  color: rgba(255,255,255,0.8);
}

/* ===== UTILITIES ===== */
.text-center { text-align: center; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }

/* ===== MATH ===== */
.math-block {
  background: #f1f3f5;
  padding: 16px 20px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 16px 0;
  text-align: center;
}
.equation-label {
  float: right;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ===== FRAMEWORK PIPELINE ===== */
.pipeline {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  padding: 24px 0;
  flex-wrap: wrap;
  margin: 24px 0;
}
.pipeline-step {
  background: var(--bg-card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 18px;
  text-align: center;
  font-size: 0.85rem;
  font-weight: 600;
  min-width: 100px;
}
.pipeline-step.highlight { border-color: var(--teal); background: rgba(22,105,122,0.06); }
.pipeline-arrow {
  font-size: 1.2rem;
  color: var(--teal);
  padding: 0 8px;
  font-weight: 700;
}

/* Axis cards */
.axis-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin: 24px 0;
}
.axis-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  border-top: 4px solid var(--teal);
}
.axis-card h4 {
  font-size: 1rem;
  color: var(--navy);
  margin-bottom: 12px;
}
.axis-card ul {
  list-style: none;
  font-size: 0.88rem;
}
.axis-card li {
  padding: 4px 0;
  padding-left: 16px;
  position: relative;
}
.axis-card li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--teal);
}

/* Print */
@media print {
  .header, .sidebar, .footer, .btn-group { display: none; }
  .page-layout { grid-template-columns: 1fr; }
  .paper-card { break-inside: avoid; }
}