:root {
  --bg: #fff;
  --fg: #1a1a2e;
  --accent: #2563eb;
  --accent-dark: #1d4ed8;
  --muted: #64748b;
  --border: #e2e8f0;
  --surface: #f8fafc;
  --code-bg: #1e293b;
  --code-fg: #e2e8f0;
  --hero-bg: #0f172a;
  --hero-fg: #f1f5f9;
  --max-w: 960px;
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 17px; scroll-behavior: smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.7;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* --- Hero --- */
.hero {
  background: var(--hero-bg);
  color: var(--hero-fg);
  padding: 4rem 1.5rem 3rem;
  text-align: center;
}
.hero h1 { font-size: 2.8rem; font-weight: 800; letter-spacing: -0.03em; margin-bottom: 0.5rem; }
.hero h1 span { color: var(--accent); }
.hero .tagline { font-size: 1.15rem; color: #94a3b8; max-width: 640px; margin: 0 auto 1.5rem; }
.hero .badges { display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap; }
.hero .badges a {
  display: inline-block;
  padding: 0.5rem 1.2rem;
  border-radius: 6px;
  font-size: 0.9rem;
  font-weight: 600;
  transition: background 0.15s;
}
.hero .badges .primary { background: var(--accent); color: #fff; }
.hero .badges .primary:hover { background: var(--accent-dark); text-decoration: none; }
.hero .badges .secondary { border: 1px solid #475569; color: #cbd5e1; }
.hero .badges .secondary:hover { border-color: #94a3b8; color: #f1f5f9; text-decoration: none; }

/* --- Compact hero for sub-pages --- */
.hero-compact { padding: 2.5rem 1.5rem 2rem; }
.hero-compact h1 { font-size: 2rem; }

/* --- Nav --- */
nav {
  position: sticky; top: 0; z-index: 10;
  background: rgba(255,255,255,0.95); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  padding: 0 1.5rem;
}
nav ul {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  gap: 1.5rem;
  list-style: none;
  overflow-x: auto;
}
nav a {
  display: block;
  padding: 0.75rem 0;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--muted);
  white-space: nowrap;
}
nav a:hover { color: var(--fg); text-decoration: none; }
nav a.active { color: var(--accent); border-bottom: 2px solid var(--accent); }

/* --- Sections --- */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 1.5rem; }
section { padding: 3rem 0; }
section + section { border-top: 1px solid var(--border); }
h2 { font-size: 1.6rem; font-weight: 700; margin-bottom: 1rem; letter-spacing: -0.02em; }
h3 { font-size: 1.15rem; font-weight: 600; margin: 1.5rem 0 0.5rem; }
h4 { font-size: 1rem; font-weight: 600; margin: 1.2rem 0 0.4rem; }
p { margin-bottom: 1rem; }
p + ul, p + ol { margin-top: -0.5rem; }
ul, ol { padding-left: 1.5rem; margin-bottom: 1rem; }
li { margin-bottom: 0.3rem; }

/* --- Code --- */
code {
  font-family: "JetBrains Mono", "Fira Code", "SF Mono", Consolas, monospace;
  font-size: 0.88em;
  background: var(--surface);
  padding: 0.15em 0.4em;
  border-radius: 4px;
}
pre {
  background: var(--code-bg);
  color: var(--code-fg);
  padding: 1.25rem 1.5rem;
  border-radius: 8px;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  line-height: 1.5;
}
pre code { background: none; padding: 0; font-size: 0.85rem; color: inherit; }

/* --- Tables --- */
table { width: 100%; border-collapse: collapse; margin-bottom: 1.5rem; font-size: 0.92rem; }
th { text-align: left; font-weight: 600; padding: 0.6rem 0.75rem; border-bottom: 2px solid var(--border); }
td { padding: 0.5rem 0.75rem; border-bottom: 1px solid var(--border); }
tr:last-child td { border-bottom: none; }

/* --- Grid cards --- */
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 1.25rem; margin-bottom: 1.5rem; }
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem;
}
.card h3 { margin-top: 0; font-size: 1.05rem; }
.card p { font-size: 0.92rem; color: var(--muted); margin-bottom: 0; }

/* --- Math block --- */
.math-block { overflow-x: auto; margin: 1rem 0 1.5rem; text-align: center; }

/* --- Mermaid --- */
.mermaid { margin: 1.5rem 0; text-align: center; }

/* --- Keyword highlights --- */
.kw { color: #7c3aed; font-weight: 600; }
.cm { color: #64748b; }
.fn { color: #2563eb; }
.st { color: #059669; }
.nb { color: #e879a0; }
.mi { color: #f59e0b; }
.op { color: #94a3b8; }

/* --- Sidebar TOC for docs --- */
.page-with-toc { display: flex; gap: 2rem; max-width: 1200px; margin: 0 auto; padding: 0 1.5rem; }
.page-with-toc .toc {
  position: sticky;
  top: 60px;
  align-self: flex-start;
  width: 220px;
  flex-shrink: 0;
  padding: 1.5rem 0;
  font-size: 0.82rem;
  max-height: calc(100vh - 60px);
  overflow-y: auto;
}
.page-with-toc .toc ul { list-style: none; padding-left: 0; }
.page-with-toc .toc li { margin-bottom: 0.4rem; }
.page-with-toc .toc a { color: var(--muted); font-weight: 500; }
.page-with-toc .toc a:hover { color: var(--fg); text-decoration: none; }
.page-with-toc .toc .toc-h3 { padding-left: 0.75rem; font-size: 0.78rem; }
.page-with-toc .content { flex: 1; min-width: 0; }

/* --- Note/tip boxes --- */
.note {
  background: #eff6ff;
  border-left: 4px solid var(--accent);
  padding: 0.75rem 1rem;
  margin-bottom: 1.5rem;
  border-radius: 0 6px 6px 0;
  font-size: 0.92rem;
}
.note strong { color: var(--accent); }

/* --- Example header tags --- */
.example-tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.2rem 0.6rem;
  border-radius: 4px;
  margin-bottom: 0.5rem;
}
.tag-sql { background: #f3e8ff; color: #7c3aed; }
.tag-python { background: #ecfdf5; color: #059669; }
.tag-shell { background: #fff7ed; color: #c2410c; }

/* --- Paper metadata --- */
.paper-meta {
  font-size: 0.88rem;
  color: var(--muted);
  margin-top: -0.5rem;
  margin-bottom: 1.25rem;
}

/* --- Footer --- */
footer {
  border-top: 1px solid var(--border);
  padding: 2rem 1.5rem;
  text-align: center;
  color: var(--muted);
  font-size: 0.85rem;
}
footer a { color: var(--accent); }

/* --- Responsive --- */
@media (max-width: 900px) {
  .page-with-toc { flex-direction: column; }
  .page-with-toc .toc {
    position: static;
    width: 100%;
    max-height: none;
    border-bottom: 1px solid var(--border);
    padding-bottom: 1rem;
  }
}
@media (max-width: 640px) {
  .hero h1 { font-size: 2rem; }
  .hero-compact h1 { font-size: 1.6rem; }
  .hero .tagline { font-size: 1rem; }
  section { padding: 2rem 0; }
  h2 { font-size: 1.35rem; }
  pre { padding: 1rem; }
}