/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #F0F7F4;
  --surface: #FFFFFF;
  --primary: #1565C0;
  --secondary: #2E7D32;
  --accent: #1B5E20;
  --text: #0D2818;
  --muted: #6E8B73;
  --line: #CDE0D0;
  --heading-font: 'Playfair Display', Georgia, serif;
  --body-font: 'Inter', 'Segoe UI', sans-serif;
  --mono-font: 'JetBrains Mono', 'Fira Code', monospace;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--body-font);
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text);
  background: var(--bg);
}

img { max-width: 100%; height: auto; display: block; }

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

/* === Container === */
.container { max-width: 900px; margin: 0 auto; padding: 0 1.5rem; }

/* === Sections === */
.section { padding: 4rem 0; }
.section-alt { background: var(--surface); }

/* === Hero === */
.hero {
  position: relative;
  min-height: 520px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  text-align: center;
}
.hero-bg {
  position: absolute; inset: 0;
  background: url('./assets/hero_bg.png') center/cover no-repeat;
  z-index: 0;
}
.hero-overlay {
  position: absolute; inset: 0;
  background: rgba(13, 40, 24, 0.82);
  z-index: 1;
}
.hero-content {
  position: relative; z-index: 2;
  max-width: 800px; padding: 3rem 1.5rem;
  color: #fff;
}
.hero h1 {
  font-family: var(--heading-font);
  font-size: 2.8rem;
  font-weight: 900;
  line-height: 1.2;
  margin-bottom: 1rem;
}
.hero-subtitle {
  font-size: 1.2rem;
  opacity: 0.9;
  margin-bottom: 0.75rem;
  line-height: 1.6;
}
.hero-authors {
  font-size: 0.95rem;
  opacity: 0.7;
  margin-bottom: 1.5rem;
}
.hero-badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  justify-content: center;
  margin-bottom: 1.5rem;
}
.chip {
  display: inline-block;
  padding: 0.3rem 0.8rem;
  border: 1px solid rgba(255,255,255,0.4);
  border-radius: 100px;
  font-size: 0.85rem;
  font-weight: 600;
  color: #fff;
  background: rgba(255,255,255,0.08);
  backdrop-filter: blur(4px);
}
.hero-actions {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}
.btn {
  display: inline-block;
  padding: 0.65rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  background: var(--primary);
  color: #fff;
  transition: background 0.2s, transform 0.2s;
}
.btn:hover { background: #0D47A1; transform: translateY(-1px); text-decoration: none; }
.btn-secondary {
  background: transparent;
  border: 1px solid rgba(255,255,255,0.5);
}
.btn-secondary:hover { background: rgba(255,255,255,0.1); }

/* === Typography === */
h2 {
  font-family: var(--heading-font);
  font-size: 2rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 1.5rem;
}
h3 {
  font-family: var(--heading-font);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.75rem;
}
p { margin-bottom: 1rem; }

/* === Abstract === */
.abstract-block {
  border-left: 4px solid var(--primary);
  padding: 1.5rem 2rem;
  background: var(--surface);
  border-radius: 0 12px 12px 0;
  font-size: 1.1rem;
  line-height: 1.9;
}
.section-alt .abstract-block { background: var(--bg); }

/* === Callout === */
.callout {
  background: rgba(21, 101, 192, 0.06);
  border: 1px solid rgba(21, 101, 192, 0.15);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  margin: 1.5rem 0;
}
.callout h3 { color: var(--primary); margin-bottom: 1rem; }
.callout ul { padding-left: 1.2rem; }
.callout li { margin-bottom: 0.5rem; }

/* === Cards === */
.card-grid { display: grid; gap: 1.5rem; margin: 2rem 0; }
.card-grid.two-col { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.card-grid.three-col { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }

.card {
  background: var(--surface);
  border-radius: 12px;
  padding: 1.5rem 2rem;
  box-shadow: 0 2px 12px rgba(0,0,0,0.06);
  transition: box-shadow 0.3s, transform 0.3s;
  border-top: 3px solid var(--line);
}
.card:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  transform: translateY(-2px);
}
.card-primary { border-top-color: var(--primary); }
.card-secondary { border-top-color: var(--secondary); }
.card-accent { border-top-color: var(--accent); }
.section-alt .card { background: var(--bg); }
.card ul { padding-left: 1.2rem; }
.card li { margin-bottom: 0.4rem; font-size: 0.95rem; }

/* === Figures === */
.figure-block {
  margin: 2rem 0;
  text-align: center;
}
.figure-block img {
  border-radius: 8px;
  border: 1px solid var(--line);
  margin: 0 auto;
  background: #fff;
  padding: 0.5rem;
}
.figure-centered img { max-width: 500px; }
.figure-block figcaption {
  margin-top: 0.75rem;
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.5;
}

/* === Metrics === */
.metric-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}
.metric-card {
  background: var(--surface);
  border-radius: 12px;
  padding: 1.5rem;
  text-align: center;
  box-shadow: 0 2px 12px rgba(0,0,0,0.06);
  border-bottom: 3px solid var(--primary);
}
.section-alt .metric-card { background: var(--bg); border-bottom-color: var(--secondary); }
.metric-value {
  display: block;
  font-family: var(--mono-font);
  font-size: 2.4rem;
  font-weight: 700;
  color: var(--primary);
  line-height: 1.2;
  margin-bottom: 0.5rem;
}
.section-alt .metric-value { color: var(--secondary); }
.metric-label {
  display: block;
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.4;
}

/* === Future Work === */
.future-work {
  padding-left: 1.5rem;
  margin: 1rem 0;
}
.future-work li {
  margin-bottom: 0.75rem;
  padding-left: 0.5rem;
}

/* === Details / Accordion === */
details {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  margin: 1rem 0;
}
.section-alt details { background: var(--bg); }
details summary {
  padding: 1rem 1.5rem;
  cursor: pointer;
  font-weight: 600;
  color: var(--primary);
  user-select: none;
}
details summary:hover { color: var(--accent); }
details[open] summary { border-bottom: 1px solid var(--line); }
details > :not(summary) { padding: 0 1.5rem 1.5rem; }

/* === References === */
.references-list {
  font-size: 0.85rem;
  color: var(--muted);
  line-height: 1.6;
  padding-left: 1.5rem;
}
.references-list li { margin-bottom: 0.4rem; }

/* === Footer === */
.footer {
  text-align: center;
  padding: 2rem;
  font-size: 0.85rem;
  color: var(--muted);
  border-top: 1px solid var(--line);
}

/* === Reveal Animation === */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* === Flecto Explanation UI === */
.flecto-note,
.flecto-callout,
.flecto-card,
.flecto-panel {
  position: relative;
  margin: 1.5rem 0;
  border-radius: 10px;
  padding: 1.25rem 1.5rem;
  padding-top: 2.5rem;
  line-height: 1.7;
}
.flecto-note::before,
.flecto-callout::before,
.flecto-card::before,
.flecto-panel::before {
  content: "\1F916  AI explanation";
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  color: #60a5fa;
  letter-spacing: 0.06em;
  display: block;
  margin-bottom: 0.5em;
  position: absolute;
  top: 0.75rem;
  left: 1.5rem;
}

.flecto-note {
  font-size: 0.93rem;
  border-left: 3px solid #60a5fa;
  background: rgba(96, 165, 250, 0.06);
}
.flecto-callout {
  background: rgba(96, 165, 250, 0.08);
  border: 1px solid rgba(96, 165, 250, 0.2);
}
.flecto-card {
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: 0 2px 8px rgba(0,0,0,0.04);
}
.section-alt .flecto-card { background: var(--bg); }
.flecto-panel {
  background: rgba(96, 165, 250, 0.04);
  border: 1px solid rgba(96, 165, 250, 0.15);
  padding: 1.5rem 2rem;
  padding-top: 2.75rem;
}
.flecto-card h4,
.flecto-panel h4 {
  font-family: var(--heading-font);
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
  color: var(--primary);
}
.flecto-card ul,
.flecto-panel ul {
  padding-left: 1.2rem;
  margin: 0.5rem 0;
}
.flecto-card li,
.flecto-panel li { margin-bottom: 0.3rem; font-size: 0.93rem; }

/* === Responsive === */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.8rem; }
  .hero-subtitle { font-size: 1rem; }
  h2 { font-size: 1.5rem; }
  .card-grid.three-col { grid-template-columns: 1fr; }
  .metric-value { font-size: 1.8rem; }
  .container { padding: 0 1rem; }
  .section { padding: 2.5rem 0; }
}

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