:root {
  --primary: #003B6E;
  --accent: #0078D4;
  --bg: #f0f4f8;
  --card-bg: #ffffff;
  --code-bg: #1a1a2e;
  --code-fg: #e2e8f0;
  --border: #d1d9e0;
  --text: #24292e;
  --muted: #586069;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* ── Navigation ── */
nav {
  background: var(--primary);
  padding: 10px 16px;
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
}

nav .brand {
  color: white;
  font-weight: 700;
  font-size: 0.9rem;
  margin-right: 6px;
  white-space: nowrap;
}

nav a {
  color: rgba(255,255,255,0.8);
  text-decoration: none;
  font-size: 0.75rem;
  padding: 3px 8px;
  border-radius: 4px;
  transition: background 0.15s;
  white-space: nowrap;
}

nav a:hover { background: rgba(255,255,255,0.2); color: white; }
nav a.active { background: rgba(255,255,255,0.25); color: white; }

/* ── Layout ── */
main {
  max-width: 920px;
  margin: 0 auto;
  padding: 20px 16px 40px;
}

.page-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}

.page-subtitle {
  color: var(--muted);
  font-size: 0.88rem;
  margin-bottom: 20px;
}

/* ── Cards / Details ── */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  margin-bottom: 14px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

details > summary {
  list-style: none;
  padding: 13px 16px;
  cursor: pointer;
  background: var(--card-bg);
  font-weight: 600;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 8px;
  user-select: none;
}

details > summary::-webkit-details-marker { display: none; }

details > summary::before {
  content: "▼";
  font-size: 0.65rem;
  color: var(--accent);
  transition: transform 0.2s;
}

details:not([open]) > summary::before {
  transform: rotate(-90deg);
}

details > summary:hover { background: #f6f8fa; }

.card-body {
  padding: 14px 16px;
  border-top: 1px solid var(--border);
}

.card-body p { margin-bottom: 10px; font-size: 0.88rem; }
.card-body p:last-child { margin-bottom: 0; }

/* ── Code blocks ── */
pre {
  background: var(--code-bg);
  color: var(--code-fg);
  padding: 14px 16px;
  border-radius: 6px;
  overflow-x: auto;
  font-size: 0.76rem;
  line-height: 1.55;
  white-space: pre;
  font-family: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Courier New', monospace;
  margin: 10px 0;
}

code {
  background: #eef0f3;
  padding: 2px 5px;
  border-radius: 3px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82em;
}

.pre-label {
  font-size: 0.7rem;
  color: var(--muted);
  font-family: monospace;
  margin-top: 12px;
  margin-bottom: 2px;
}

/* ── Function reference links ── */
.fn-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 8px 0;
}

.fn-ref {
  display: inline-flex;
  align-items: baseline;
  gap: 5px;
  background: #eef3fb;
  border: 1px solid #c8d8f0;
  border-radius: 5px;
  padding: 4px 9px;
  font-size: 0.78rem;
  text-decoration: none;
  color: var(--text);
  transition: all 0.15s;
  font-family: monospace;
}

.fn-ref:hover {
  background: #d9eaff;
  border-color: var(--accent);
  color: #003380;
}

.fn-ref .file-loc {
  color: var(--muted);
  font-size: 0.7rem;
  font-family: sans-serif;
}

/* ── Data flow diagram ── */
.flow-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
  margin: 20px auto;
  max-width: 360px;
}

.flow-node {
  width: 100%;
  background: var(--card-bg);
  border: 2px solid var(--primary);
  border-radius: 8px;
  padding: 10px 16px;
  text-align: center;
  text-decoration: none;
  color: var(--text);
  transition: all 0.18s;
  display: block;
}

.flow-node:hover {
  background: var(--primary);
  color: white;
  transform: scale(1.02);
  box-shadow: 0 4px 12px rgba(0,59,110,0.3);
}

.flow-node .fn-label {
  font-weight: 700;
  font-size: 0.92rem;
  color: var(--primary);
}

.flow-node:hover .fn-label { color: white; }

.flow-node .fn-file {
  font-size: 0.72rem;
  color: var(--muted);
  margin-top: 2px;
  font-family: monospace;
}

.flow-node:hover .fn-file { color: rgba(255,255,255,0.75); }

.flow-arrow {
  font-size: 1.3rem;
  color: var(--accent);
  line-height: 1;
  padding: 3px 0;
  text-align: center;
}

.flow-label {
  font-size: 0.68rem;
  color: var(--muted);
  text-align: center;
  margin-top: -2px;
  margin-bottom: 2px;
  font-style: italic;
}

/* ── Tables ── */
.table-wrap { overflow-x: auto; }

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.82rem;
}

th {
  background: #eef2f7;
  padding: 8px 10px;
  text-align: left;
  font-weight: 600;
  border-bottom: 2px solid var(--border);
  white-space: nowrap;
}

td {
  padding: 7px 10px;
  border-bottom: 1px solid #eff1f3;
  vertical-align: top;
}

tr:last-child td { border-bottom: none; }
tr:hover td { background: #fafbfd; }

td code { font-size: 0.8rem; }

/* ── Badges ── */
.badge {
  display: inline-block;
  padding: 2px 7px;
  border-radius: 10px;
  font-size: 0.68rem;
  font-weight: 600;
  background: #e3f1ff;
  color: #0056b3;
  margin-left: 5px;
}

.badge.green { background: #e6f9ee; color: #1a7f37; }
.badge.orange { background: #fff3e0; color: #b85c00; }
.badge.purple { background: #f3e8ff; color: #7c3aed; }

/* ── GitHub link ── */
.gh-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  color: var(--accent);
  font-size: 0.78rem;
  text-decoration: none;
  font-family: monospace;
}

.gh-link:hover { text-decoration: underline; }

/* ── Section heading ── */
h2 {
  font-size: 1.05rem;
  color: var(--primary);
  margin: 20px 0 10px;
  padding-bottom: 5px;
  border-bottom: 2px solid var(--border);
}

h3 {
  font-size: 0.9rem;
  margin-bottom: 6px;
}

/* ── Info callout ── */
.callout {
  background: #e8f4fd;
  border-left: 4px solid var(--accent);
  padding: 10px 14px;
  border-radius: 0 6px 6px 0;
  font-size: 0.84rem;
  margin: 10px 0;
}

.callout strong { color: var(--primary); }

/* ── Responsive ── */
@media (max-width: 600px) {
  nav { padding: 8px 12px; }
  nav a { font-size: 0.7rem; padding: 3px 6px; }
  .page-title { font-size: 1.25rem; }
  pre { font-size: 0.68rem; padding: 10px 12px; }
  table { font-size: 0.75rem; }
  th, td { padding: 6px 8px; }
}