@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Serif:ital,wght@0,400;0,500;0,600;1,400&family=IBM+Plex+Sans:wght@400;500;600&family=IBM+Plex+Mono:wght@400;500&display=swap');

:root {
  --paper: #EDEFEA;
  --surface: #F8F9F6;
  --ink: #1B2321;
  --ink-muted: #5B655F;
  --line: #D3D8CF;
  --accent: #1F4E6E;
  --accent-soft: #DCE6E9;
  --highlight: #B4791F;
  --highlight-soft: #F3E4CB;
}
@media (prefers-color-scheme: dark) {
  :root {
    --paper: #12161A;
    --surface: #191E22;
    --ink: #E7EBE6;
    --ink-muted: #97A19B;
    --line: #2B3238;
    --accent: #7CB3D4;
    --accent-soft: #1E2E37;
    --highlight: #E3A94C;
    --highlight-soft: #2E2718;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: 'IBM Plex Sans', system-ui, sans-serif;
  line-height: 1.6;
}
a { color: var(--accent); }
.mono { font-family: 'IBM Plex Mono', monospace; }
.wrap { max-width: 920px; margin: 0 auto; padding: 0 28px; }
img { max-width: 100%; height: auto; border-radius: 6px; border: 1px solid var(--line); }

/* ---- site chrome ---- */
.site-nav {
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.82rem;
}
.site-nav a { color: var(--ink); text-decoration: none; }
.site-nav a:hover { color: var(--accent); }

/* ---- doc-cover hero (homepage) ---- */
.cover { padding: 72px 0 48px; border-bottom: 1px solid var(--line); }
.cover .eyebrow {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 18px;
}
.cover h1 {
  font-family: 'IBM Plex Serif', Georgia, serif;
  font-weight: 600;
  font-size: 3rem;
  margin: 0 0 6px;
  text-wrap: balance;
}
.cover .role {
  font-family: 'IBM Plex Serif', serif;
  font-style: italic;
  font-size: 1.15rem;
  color: var(--ink-muted);
  margin: 0 0 26px;
}
.cover .abstract { max-width: 62ch; font-size: 1.05rem; margin: 0 0 28px; }
.cover .stat-line {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.82rem;
  color: var(--ink-muted);
  display: flex;
  gap: 22px;
  flex-wrap: wrap;
}
.cover .stat-line strong { color: var(--ink); font-weight: 500; }

/* ---- index (homepage list) ---- */
.index { padding: 40px 0 80px; }
.part {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin: 40px 0 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
}
.part:first-child { margin-top: 0; }
.row {
  display: grid;
  grid-template-columns: 44px 1fr auto;
  gap: 18px;
  align-items: baseline;
  padding: 14px 10px;
  border-radius: 3px;
  transition: background 0.12s ease;
  text-decoration: none;
}
.row:hover { background: var(--surface); }
.row .idx { font-family: 'IBM Plex Mono', monospace; font-size: 0.82rem; color: var(--ink-muted); }
.row .main-title {
  font-family: 'IBM Plex Serif', serif;
  font-size: 1.08rem;
  color: var(--ink);
}
.row:hover .main-title { color: var(--accent); }
.row .rationale { font-size: 0.88rem; color: var(--ink-muted); margin-top: 4px; max-width: 60ch; }
.row .tag {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 8px;
  border-radius: 3px;
  white-space: nowrap;
  align-self: start;
}

/* ---- article page ---- */
.article-wrap { max-width: 680px; margin: 0 auto; padding: 40px 28px 100px; }
.breadcrumb { font-family: 'IBM Plex Mono', monospace; font-size: 0.78rem; color: var(--ink-muted); margin-bottom: 22px; }
.breadcrumb a { color: var(--ink-muted); }
.art-tag {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 9px;
  border-radius: 3px;
}
.art-header h1 { font-family: 'IBM Plex Serif', serif; font-weight: 600; font-size: 2.1rem; margin: 14px 0 10px; text-wrap: balance; }
.art-meta { font-family: 'IBM Plex Mono', monospace; font-size: 0.8rem; color: var(--ink-muted); margin-bottom: 32px; }
.art-meta a { color: var(--accent); }
.why {
  border-left: 3px solid var(--highlight);
  background: var(--highlight-soft);
  padding: 14px 18px;
  margin: 0 0 36px;
  border-radius: 0 4px 4px 0;
}
.why .label { font-family: 'IBM Plex Mono', monospace; font-size: 0.72rem; letter-spacing: 0.08em; text-transform: uppercase; color: var(--highlight); margin: 0 0 6px; }
.why p { margin: 0; font-size: 0.95rem; }
.art-body { font-size: 1rem; }
.art-body h2 { font-family: 'IBM Plex Serif', serif; font-size: 1.4rem; margin: 1.8em 0 0.6em; }
.art-body h3 { font-family: 'IBM Plex Serif', serif; font-size: 1.15rem; margin: 1.4em 0 0.5em; }
.art-body p { margin: 0 0 1.1em; }
.art-body ul, .art-body ol { padding-left: 1.3em; }
.art-body li { margin: 0.35em 0; }
.art-body .callout {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 6px;
  padding: 14px 18px;
  margin: 1.3em 0;
  font-size: 0.95rem;
}
.art-body .callout p:last-child { margin-bottom: 0; }
.art-body .callout .callout-label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.7rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-muted);
  margin: 0 0 6px;
}
.art-body table { width: 100%; border-collapse: collapse; margin: 1.4em 0; font-size: 0.9rem; }
.art-body th, .art-body td { border: 1px solid var(--line); padding: 8px 12px; text-align: left; }
.art-body th { background: var(--surface); font-family: 'IBM Plex Mono', monospace; font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.03em; }
.art-body code { background: var(--surface); padding: 0.15em 0.4em; border-radius: 4px; font-size: 0.88em; font-family: 'IBM Plex Mono', monospace; }

.article-footer { padding: 32px 0 0; margin-top: 40px; border-top: 1px solid var(--line); font-family: 'IBM Plex Mono', monospace; font-size: 0.85rem; }

.site-footer {
  border-top: 1px solid var(--line);
  padding: 32px 0;
  color: var(--ink-muted);
  font-size: 0.85rem;
  text-align: center;
  font-family: 'IBM Plex Mono', monospace;
}

@media (max-width: 600px) {
  .cover h1 { font-size: 2.2rem; }
  .row { grid-template-columns: 32px 1fr; }
  .row .tag { grid-column: 2; margin-top: 6px; }
}