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

:root {
  --bg: #0d1117;
  --surface: #161b22;
  --surface-2: #1c2129;
  --border: #30363d;
  --text: #e6edf3;
  --text-muted: #8b949e;
  --accent: #58a6ff;
  --base-color: #8b949e;
  --sft-color: #58a6ff;
  --grpo-color: #3fb950;
  --dpo-color: #d2a8ff;
  --eval-color: #f0883e;
  --serve-color: #f778ba;
  --font-mono: "JetBrains Mono", "Fira Code", "SF Mono", monospace;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

html {
  scroll-behavior: smooth;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

/* ── Layout ─────────────────────────────────────────────────── */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
}

section {
  padding: 64px 0;
  border-bottom: 1px solid var(--border);
}
section:last-child {
  border-bottom: none;
}

h2 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 32px;
  letter-spacing: -0.02em;
}

h2 .section-icon {
  margin-right: 10px;
  opacity: 0.7;
}

/* ── Hero ───────────────────────────────────────────────────── */
.hero {
  text-align: center;
  padding: 96px 0 64px;
}

.hero h1 {
  font-family: var(--font-mono);
  font-size: 3.5rem;
  font-weight: 800;
  letter-spacing: -0.04em;
  background: linear-gradient(135deg, var(--sft-color), var(--grpo-color), var(--dpo-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero .tagline {
  font-size: 1.25rem;
  color: var(--text-muted);
  margin-top: 12px;
  font-weight: 400;
}

.hero .links {
  margin-top: 28px;
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.hero .links a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.9rem;
  transition: background 0.2s, transform 0.15s;
}

.btn-primary {
  background: var(--accent);
  color: var(--bg) !important;
  -webkit-text-fill-color: var(--bg);
}
.btn-primary:hover {
  background: #79c0ff;
  text-decoration: none;
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--surface);
  border: 1px solid var(--border);
}
.btn-secondary:hover {
  background: var(--surface-2);
  text-decoration: none;
  transform: translateY(-1px);
}

/* ── Pipeline ───────────────────────────────────────────────── */
.pipeline-flow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0;
  flex-wrap: wrap;
  padding: 20px 0;
}

.pipeline-node {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 20px 24px;
  border-radius: 12px;
  background: var(--surface);
  border: 2px solid var(--border);
  min-width: 110px;
  transition: border-color 0.2s, transform 0.15s;
}

.pipeline-node:hover {
  transform: translateY(-2px);
}

.pipeline-node .node-label {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.pipeline-node .node-desc {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-align: center;
}

.pipeline-node.base { border-color: var(--base-color); }
.pipeline-node.base .node-label { color: var(--base-color); }
.pipeline-node.sft { border-color: var(--sft-color); }
.pipeline-node.sft .node-label { color: var(--sft-color); }
.pipeline-node.grpo { border-color: var(--grpo-color); }
.pipeline-node.grpo .node-label { color: var(--grpo-color); }
.pipeline-node.dpo { border-color: var(--dpo-color); }
.pipeline-node.dpo .node-label { color: var(--dpo-color); }
.pipeline-node.eval { border-color: var(--eval-color); }
.pipeline-node.eval .node-label { color: var(--eval-color); }
.pipeline-node.serve { border-color: var(--serve-color); }
.pipeline-node.serve .node-label { color: var(--serve-color); }

.pipeline-arrow {
  font-size: 1.4rem;
  color: var(--text-muted);
  padding: 0 6px;
  user-select: none;
}

.pipeline-branch {
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: center;
}

.pipeline-branch-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

/* ── Benchmark table ────────────────────────────────────────── */
.bench-table-wrapper {
  overflow-x: auto;
  border-radius: 12px;
  border: 1px solid var(--border);
}

.bench-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.bench-table th,
.bench-table td {
  padding: 14px 20px;
  text-align: center;
  border-bottom: 1px solid var(--border);
}

.bench-table th {
  background: var(--surface);
  font-weight: 700;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.bench-table th.col-base { color: var(--base-color); }
.bench-table th.col-sft { color: var(--sft-color); }
.bench-table th.col-grpo { color: var(--grpo-color); }
.bench-table th.col-dpo { color: var(--dpo-color); }

.bench-table td:first-child {
  text-align: left;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 0.85rem;
}

.bench-table tbody tr:hover {
  background: var(--surface);
}

.bench-table tbody tr:last-child td {
  border-bottom: none;
}

.score-best {
  color: var(--grpo-color);
  font-weight: 700;
}

.score-bar {
  display: inline-block;
  height: 6px;
  border-radius: 3px;
  margin-top: 6px;
  opacity: 0.6;
  transition: width 0.4s ease;
}

/* ── Charts ─────────────────────────────────────────────────── */
.charts-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.chart-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
}

.chart-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text-muted);
}

.chart-card canvas {
  width: 100% !important;
}

/* ── Reasoning examples ─────────────────────────────────────── */
.example-prompt {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px 24px;
  margin-bottom: 24px;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent);
}

.example-prompt .label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 8px;
  font-family: var(--font-sans);
  font-weight: 700;
}

.examples-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.example-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px;
  display: flex;
  flex-direction: column;
}

.example-card .stage-badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 4px 10px;
  border-radius: 6px;
  margin-bottom: 14px;
  width: fit-content;
}

.example-card .stage-badge.base {
  background: rgba(139, 148, 158, 0.15);
  color: var(--base-color);
}
.example-card .stage-badge.sft {
  background: rgba(88, 166, 255, 0.15);
  color: var(--sft-color);
}
.example-card .stage-badge.grpo {
  background: rgba(63, 185, 80, 0.15);
  color: var(--grpo-color);
}

.example-card .response {
  font-size: 0.85rem;
  line-height: 1.7;
  color: var(--text);
  white-space: pre-wrap;
  font-family: var(--font-mono);
  flex: 1;
}

.example-card .response .boxed {
  display: inline-block;
  background: rgba(63, 185, 80, 0.12);
  border: 1px solid rgba(63, 185, 80, 0.3);
  border-radius: 4px;
  padding: 2px 8px;
  font-weight: 700;
  color: var(--grpo-color);
}

/* ── Notebooks ──────────────────────────────────────────────── */
.notebooks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.notebook-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 20px 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: border-color 0.2s, transform 0.15s;
}

.notebook-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.notebook-card h3 {
  font-size: 1rem;
  font-weight: 700;
}

.notebook-card p {
  font-size: 0.85rem;
  color: var(--text-muted);
  flex: 1;
}

.notebook-card .badge-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

.notebook-card .badge-row img {
  height: 20px;
}

/* ── Footer ─────────────────────────────────────────────────── */
.footer {
  text-align: center;
  padding: 40px 0;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ── Responsive ─────────────────────────────────────────────── */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.4rem;
  }

  .pipeline-flow {
    flex-direction: column;
  }

  .pipeline-arrow {
    transform: rotate(90deg);
  }

  .charts-grid {
    grid-template-columns: 1fr;
  }

  .examples-grid {
    grid-template-columns: 1fr;
  }
}