:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #5a5a5a;
  --rule: #e6e0d4;
  --accent: #8b2a1f;
  --side: #faf7f1;
  --link: #6a0f08;
  --max-w: 720px;
}
* { box-sizing: border-box; }
html, body { background: var(--bg); color: var(--fg); margin: 0; padding: 0;
  font-family: 'Iowan Old Style', 'Palatino Linotype', Palatino, 'Book Antiqua', Georgia, serif;
  line-height: 1.68; font-size: 17px; }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Header */
header.site {
  border-bottom: 1px solid var(--rule);
  padding: 14px 24px;
  display: flex; align-items: baseline; gap: 24px;
  position: sticky; top: 0; background: var(--bg); z-index: 50;
}
header.site .brand { font-weight: 600; font-size: 17px; color: var(--accent); letter-spacing: 0.01em; }
header.site nav a { color: var(--fg); margin-right: 16px; font-size: 14px; }
header.site nav a:hover { color: var(--accent); }
header.site nav a.active { color: var(--accent); font-weight: 600; }

/* Three-column layout */
.layout {
  display: grid;
  grid-template-columns: 240px minmax(0, var(--max-w)) 280px;
  gap: 36px;
  max-width: 1340px;
  margin: 0 auto;
  padding: 28px 24px 80px;
}

/* Left column: in-doc nav */
.col-left {
  position: sticky; top: 70px; align-self: start;
  max-height: calc(100vh - 100px); overflow-y: auto;
  padding: 4px;
}
.col-left h3 {
  font-size: 11px; text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--muted); margin: 0 0 10px; font-weight: 600;
}
.col-left ul { list-style: none; padding: 0; margin: 0 0 18px; }
.col-left li { margin: 2px 0; }
.col-left a {
  display: block; padding: 4px 8px; border-radius: 3px;
  color: var(--fg); font-size: 13px; line-height: 1.4;
}
.col-left a:hover { background: var(--side); color: var(--accent); text-decoration: none; }
.col-left .l1 { font-weight: 600; margin-top: 10px; }
.col-left .l2 { padding-left: 14px; }
.col-left .l3 { padding-left: 26px; color: var(--muted); font-size: 12px; }

/* Middle column: text */
main {
  min-width: 0;
  padding-bottom: 60px;
}
main h1 {
  font-size: 32px; line-height: 1.18; margin: 0 0 0.5em;
  color: var(--accent);
  border-bottom: 2px solid var(--rule); padding-bottom: 10px;
}
main h2 {
  font-size: 24px; line-height: 1.25; margin: 1.6em 0 0.5em;
  color: var(--accent);
}
main h3 {
  font-size: 19px; line-height: 1.3; margin: 1.4em 0 0.4em;
  color: #2a2a2a; font-weight: 600;
}
main h4 { font-size: 17px; margin: 1.2em 0 0.4em; font-weight: 600; }
main p { margin: 0 0 1em; }
main p, main li { hyphens: auto; }
main strong { color: #1a1a1a; }
main em { color: #2a2a2a; }
main blockquote {
  border-left: 3px solid var(--accent);
  padding: 4px 0 4px 18px; margin: 1em 0;
  color: var(--muted); font-style: italic;
}
main code {
  font-family: 'SF Mono', Menlo, Consolas, monospace;
  background: var(--side); padding: 1px 5px; border-radius: 3px; font-size: 14.5px;
}
main pre { background: var(--side); padding: 14px 18px; border-radius: 4px; overflow-x: auto; font-size: 13.5px; line-height: 1.5; }
main pre code { background: transparent; padding: 0; }
main table { width: 100%; border-collapse: collapse; margin: 1.2em 0; font-size: 14.5px; }
main th, main td { border: 1px solid var(--rule); padding: 7px 11px; text-align: left; vertical-align: top; }
main th { background: var(--side); font-weight: 600; }
main hr { border: none; border-top: 1px solid var(--rule); margin: 2em 0; }
main .footnote { font-size: 14px; line-height: 1.55; margin-top: 2em; padding-top: 1em; border-top: 1px solid var(--rule); color: var(--muted); }
main .footnote ol { padding-left: 22px; }
main sup a { text-decoration: none; }

/* Diagrams */
figure.diagram {
  margin: 1.8em 0; padding: 16px;
  border: 1px solid var(--rule); border-radius: 6px; background: #fdfcf8;
}
figure.diagram svg { width: 100%; height: auto; display: block; }
figure.diagram figcaption {
  font-size: 13.5px; color: var(--muted); margin-top: 10px;
  padding-top: 8px; border-top: 1px dashed var(--rule);
  line-height: 1.5;
}

/* Right column: related */
.col-right {
  position: sticky; top: 70px; align-self: start;
  max-height: calc(100vh - 100px); overflow-y: auto;
  padding: 4px;
}
.col-right h3 {
  font-size: 11px; text-transform: uppercase; letter-spacing: 0.1em;
  color: var(--muted); margin: 0 0 10px; font-weight: 600;
}
.col-right .card {
  border: 1px solid var(--rule); border-radius: 4px;
  padding: 12px 14px; margin-bottom: 12px;
  background: #fff;
}
.col-right .card a { color: var(--fg); font-weight: 600; font-size: 14px; }
.col-right .card p { font-size: 12.5px; color: var(--muted); margin: 4px 0 0; line-height: 1.4; }
.col-right .card.accent { border-color: var(--accent); }
.col-right .card.accent a { color: var(--accent); }
.col-right .src-list { list-style: none; padding: 0; margin: 0; font-size: 13px; }
.col-right .src-list li { margin: 6px 0; padding-left: 12px; position: relative; }
.col-right .src-list li::before { content: "·"; position: absolute; left: 0; color: var(--accent); font-weight: 700; }

/* Home page hero */
.hero {
  text-align: center; padding: 40px 0 30px; border-bottom: 1px solid var(--rule);
}
.hero h1 { border: none; font-size: 38px; margin: 0; }
.hero .tag { color: var(--muted); font-size: 17px; font-style: italic; margin: 8px 0 0; }
.cards {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 18px; margin: 36px 0;
}
.cards .card {
  border: 1px solid var(--rule); border-radius: 6px;
  padding: 18px 20px; background: #fff;
  transition: border-color 0.15s;
}
.cards .card:hover { border-color: var(--accent); }
.cards .card h3 { margin: 0 0 6px; font-size: 17px; color: var(--accent); }
.cards .card p { font-size: 14.5px; color: var(--fg); margin: 0 0 10px; line-height: 1.55; }
.cards .card a { font-size: 13.5px; font-weight: 600; }

/* Reading progress bar */
.progress { position: fixed; top: 0; left: 0; right: 0; height: 2px; background: rgba(0,0,0,0.04); z-index: 100; }
.progress-bar { height: 100%; background: var(--accent); width: 0%; transition: width 0.1s; }

/* Footer */
footer.site {
  border-top: 1px solid var(--rule);
  padding: 24px; text-align: center; color: var(--muted); font-size: 13px;
  margin-top: 60px;
}

/* Mobile */
@media (max-width: 1100px) {
  .layout { grid-template-columns: 1fr; padding: 20px 18px 60px; }
  .col-left, .col-right { position: relative; max-height: none; }
}