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

:root {
  --bg:           #0d1117;
  --surface:      #161b22;
  --surface-2:    #1c2128;
  --border:       #30363d;
  --border-light: #21262d;
  --text:         #e6edf3;
  --text-muted:   #8b949e;
  --text-dim:     #6e7681;
  --blue:         #58a6ff;
  --green:        #3fb950;
  --red:          #f85149;
  --yellow:       #d29922;
  --purple:       #bc8cff;
  --orange:       #f0883e;
  --sidebar-w:    240px;
  --radius:       8px;
  --font-mono:    'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
}

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.7;
  display: flex;
  min-height: 100vh;
}

/* ── Sidebar ─────────────────────────────────────────────────────── */
.sidebar {
  width: var(--sidebar-w);
  height: 100vh;
  background: var(--surface);
  border-right: 1px solid var(--border);
  position: fixed;
  top: 0; left: 0;
  overflow-y: auto;
  z-index: 100;
  padding: 0 0 40px;
}
.sidebar-logo {
  padding: 24px 20px 20px;
  border-bottom: 1px solid var(--border);
}
.sidebar-logo a { text-decoration: none; }
.sidebar-logo h1 {
  font-size: 15px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.02em;
}
.sidebar-logo .tagline {
  font-size: 11px;
  color: var(--text-muted);
  margin-top: 3px;
}
.radar-badge {
  display: inline-block;
  background: linear-gradient(135deg, #1f6feb 0%, #388bfd 100%);
  color: #fff;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  padding: 2px 7px;
  border-radius: 10px;
  margin-bottom: 8px;
  text-transform: uppercase;
}
.sidebar nav { padding: 12px 0 24px; }

/* Home link */
.sidebar a.nav-home {
  display: block;
  padding: 7px 20px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: all 0.15s;
  margin-bottom: 6px;
}
.sidebar a.nav-home:hover { color: var(--blue); background: var(--surface-2); }
.sidebar a.nav-home.active { color: var(--blue); }

/* Section-level page links */
.sidebar a.nav-page {
  display: block;
  padding: 6px 20px;
  font-size: 12px;
  font-weight: 700;
  color: var(--text-dim);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  border-left: 2px solid transparent;
  margin-top: 14px;
  transition: all 0.15s;
}
.sidebar a.nav-page:hover { color: var(--text); }
.sidebar a.nav-page.current { color: var(--text); }

/* Sub-section links */
.sidebar a.nav-sub {
  display: block;
  padding: 4px 20px 4px 30px;
  font-size: 12px;
  color: var(--text-dim);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: all 0.15s;
  line-height: 1.45;
}
.sidebar a.nav-sub:hover { color: var(--text); background: var(--surface-2); }
.sidebar a.nav-sub.active {
  color: var(--blue);
  border-left-color: var(--blue);
  background: rgba(88,166,255,0.06);
}

/* Legacy fallback — keep for any stray .nav-section divs */
.nav-section {
  padding: 16px 20px 4px;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-dim);
}

/* ── Main content ────────────────────────────────────────────────── */
main {
  margin-left: var(--sidebar-w);
  flex: 1;
  max-width: 900px;
  padding: 48px 48px 80px;
}

/* ── Page header ─────────────────────────────────────────────────── */
.page-header {
  border-bottom: 1px solid var(--border);
  padding-bottom: 32px;
  margin-bottom: 48px;
}
.page-header .eyebrow {
  font-size: 12px;
  color: var(--blue);
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 10px;
}
.page-header h1 {
  font-size: 30px;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 14px;
  color: var(--text);
}
.page-header .subtitle {
  color: var(--text-muted);
  font-size: 15px;
  max-width: 620px;
  line-height: 1.7;
}

/* ── Typography ──────────────────────────────────────────────────── */
h2 { font-size: 22px; font-weight: 700; color: var(--text); margin: 40px 0 12px; }
h3 { font-size: 17px; font-weight: 600; color: var(--text); margin: 32px 0 12px; }
h3:first-child { margin-top: 0; }
p { color: var(--text-muted); margin-bottom: 14px; line-height: 1.75; }
strong { color: var(--text); font-weight: 600; }
em { color: var(--text); font-style: italic; }

/* ── Section header ──────────────────────────────────────────────── */
.section-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 28px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
}
.section-icon {
  width: 36px; height: 36px;
  border-radius: 8px;
  display: flex; align-items: center; justify-content: center;
  font-size: 18px; flex-shrink: 0;
}
.icon-blue   { background: rgba(88,166,255,0.12); }
.icon-green  { background: rgba(63,185,80,0.12); }
.icon-purple { background: rgba(188,140,255,0.12); }
.icon-yellow { background: rgba(210,153,34,0.12); }
.section-header h2 { font-size: 22px; font-weight: 700; margin: 0; }
.section-header .section-sub { font-size: 13px; color: var(--text-muted); margin-top: 2px; }

/* ── Cards ───────────────────────────────────────────────────────── */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin-bottom: 16px;
}
.card h4 { font-size: 13px; font-weight: 700; color: var(--text); margin-bottom: 6px; }
.card p { font-size: 13px; margin-bottom: 0; }

.card-grid   { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-bottom: 16px; }
.card-grid-3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 16px; margin-bottom: 16px; }

/* ── Callouts ────────────────────────────────────────────────────── */
.callout {
  border-left: 3px solid;
  padding: 14px 18px;
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 20px 0;
  font-size: 13.5px;
  line-height: 1.65;
}
.callout-red    { border-color: var(--red);    background: rgba(248,81,73,0.08);  color: #ffa8a3; }
.callout-green  { border-color: var(--green);  background: rgba(63,185,80,0.08);  color: #7ee787; }
.callout-yellow { border-color: var(--yellow); background: rgba(210,153,34,0.08); color: #e3b341; }
.callout-blue   { border-color: var(--blue);   background: rgba(88,166,255,0.08); color: #a5c8ff; }
.callout strong { color: inherit; }

/* ── Code ────────────────────────────────────────────────────────── */
code {
  font-family: var(--font-mono);
  font-size: 12.5px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 1px 5px;
  color: var(--orange);
}
pre {
  font-family: var(--font-mono);
  font-size: 12.5px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 18px;
  overflow-x: auto;
  color: #a5c8ff;
  line-height: 1.6;
  margin: 16px 0;
}
pre .comment   { color: var(--text-dim); }
pre .highlight { color: var(--green); }
pre .key       { color: var(--orange); }

/* ── Badges & pills ──────────────────────────────────────────────── */
.badge {
  display: inline-flex; align-items: center; gap: 5px;
  font-size: 11px; font-weight: 700;
  padding: 2px 8px; border-radius: 12px; white-space: nowrap;
}
.badge::before { content: '●'; font-size: 8px; }
.badge-green  { background: rgba(63,185,80,0.15);  color: var(--green); }
.badge-red    { background: rgba(248,81,73,0.15);  color: var(--red); }
.badge-yellow { background: rgba(210,153,34,0.15); color: var(--yellow); }
.badge-blue   { background: rgba(88,166,255,0.15); color: var(--blue); }

.pill {
  font-size: 11px; font-weight: 600;
  padding: 3px 10px; border-radius: 20px; border: 1px solid;
}
.pill-blue   { color: var(--blue);   border-color: rgba(88,166,255,0.4);  background: rgba(88,166,255,0.08); }
.pill-green  { color: var(--green);  border-color: rgba(63,185,80,0.4);   background: rgba(63,185,80,0.08); }
.pill-yellow { color: var(--yellow); border-color: rgba(210,153,34,0.4);  background: rgba(210,153,34,0.08); }
.pill-purple { color: var(--purple); border-color: rgba(188,140,255,0.4); background: rgba(188,140,255,0.08); }
.pill-red    { color: var(--red);    border-color: rgba(248,81,73,0.4);   background: rgba(248,81,73,0.08); }
.pill-row    { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 20px; }

/* ── Tables ──────────────────────────────────────────────────────── */
.table-wrap { overflow-x: auto; margin: 16px 0; }
table { width: 100%; border-collapse: collapse; font-size: 13px; }
th {
  background: var(--surface-2); color: var(--text-muted);
  font-size: 11px; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.06em; padding: 10px 14px; text-align: left;
  border-bottom: 1px solid var(--border);
}
td { padding: 10px 14px; border-bottom: 1px solid var(--border-light); color: var(--text-muted); vertical-align: top; }
tr:last-child td { border-bottom: none; }
td strong { color: var(--text); }

/* ── Step list ───────────────────────────────────────────────────── */
.step-list { margin: 12px 0 20px; }
.step {
  display: flex; gap: 14px;
  padding: 10px 0;
  border-bottom: 1px solid var(--border-light);
}
.step:last-child { border-bottom: none; }
.step-num {
  width: 26px; height: 26px;
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 700; color: var(--text-muted);
  flex-shrink: 0; margin-top: 1px;
}
.step-content { flex: 1; }
.step-title { font-size: 13.5px; font-weight: 600; color: var(--text); margin-bottom: 2px; }
.step-body  { font-size: 12.5px; color: var(--text-muted); }

/* ── Sequence diagram ────────────────────────────────────────────── */
.sequence-diagram {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 28px; margin: 20px 0; overflow-x: auto;
}
.seq-header { display: grid; grid-template-columns: 1fr 80px 1fr; gap: 0; margin-bottom: 20px; }
.seq-actor {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: 6px; text-align: center; padding: 10px 16px;
}
.seq-actor .actor-name { font-size: 13px; font-weight: 700; color: var(--text); }
.seq-actor .actor-desc { font-size: 11px; color: var(--text-muted); margin-top: 2px; }

/* ── Diagram wrap ────────────────────────────────────────────────── */
.diagram-wrap {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 28px; margin: 20px 0; overflow-x: auto;
}
.diagram-wrap svg { display: block; max-width: 100%; }

/* ── Algo cards ──────────────────────────────────────────────────── */
.algo-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 18px 20px;
}
.algo-card .algo-tag { font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.07em; margin-bottom: 6px; }
.algo-card h4 { font-size: 14px; font-weight: 700; color: var(--text); margin-bottom: 4px; }
.algo-card .fips { font-family: var(--font-mono); font-size: 11px; color: var(--blue); margin-bottom: 8px; }
.algo-card p { font-size: 12.5px; margin-bottom: 0; }

/* ── Page nav (prev/next) ────────────────────────────────────────── */
.page-nav {
  display: flex; justify-content: space-between; align-items: center;
  margin-top: 56px; padding-top: 24px;
  border-top: 1px solid var(--border);
  gap: 16px;
}
.page-nav a {
  display: flex; flex-direction: column; gap: 3px;
  padding: 12px 16px; border-radius: var(--radius);
  border: 1px solid var(--border); background: var(--surface);
  text-decoration: none; color: var(--text-muted);
  transition: all 0.15s; max-width: 260px;
}
.page-nav a:hover { border-color: var(--blue); color: var(--text); background: rgba(88,166,255,0.05); }
.page-nav .nav-label { font-size: 11px; color: var(--text-dim); font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; }
.page-nav .nav-title { font-size: 13px; font-weight: 600; color: var(--text); }
.page-nav .next { text-align: right; margin-left: auto; }

/* ── Footer ──────────────────────────────────────────────────────── */
footer {
  border-top: 1px solid var(--border); padding: 24px 0 0;
  margin-top: 40px; font-size: 12px; color: var(--text-dim);
}
footer a { color: var(--blue); text-decoration: none; }

/* ── Responsive ──────────────────────────────────────────────────── */
@media (max-width: 800px) {
  .sidebar { display: none; }
  main { margin-left: 0; padding: 24px; }
  .card-grid, .card-grid-3 { grid-template-columns: 1fr; }
  .page-nav { flex-direction: column; }
  .page-nav .next { margin-left: 0; text-align: left; }
}