/* Spatiotemporal Composability & Cordis — study book. Light only. */
* { box-sizing: border-box; }
:root {
  --bg: #fdfcf9; --fg: #24292e; --fg2: #444c56; --muted: #6a737d;
  --line: #e1e4e8; --card: #ffffff; --accent: #0b5fbd; --accent2: #08468c;
  --code-bg: #f4f2ec; --code-fg: #2f363d;
  --thm: #eef4fb; --thm-line: #c9dcf3;
  --olai: #edf7f0; --olai-line: #b9e0c6; --olai-fg: #1e5a3a;
  --warn: #fdf6e3; --warn-line: #f0d9a0; --warn-fg: #7a4d0b;
  --hs: #f4f1fa; --hs-line: #d9cff0; --hs-fg: #47307a;
  --serif: "Charter", "Iowan Old Style", "Palatino Linotype", "Book Antiqua", "Source Serif Pro", "Georgia", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Roboto, sans-serif;
  --mono: "JetBrains Mono", "Fira Code", "SFMono-Regular", Menlo, Consolas, monospace;
  --math: "STIX Two Math", "Cambria Math", "Latin Modern Math", "Charter", "Times New Roman", serif;
}
html { scroll-behavior: smooth; }
body { margin: 0; padding: 0; font-family: var(--serif); background: var(--bg); color: var(--fg); line-height: 1.7; font-size: 18px; }
.layout { display: grid; grid-template-columns: 250px minmax(0, 1fr); max-width: 1120px; margin: 0 auto; }
nav.toc { position: sticky; top: 0; align-self: start; height: 100vh; overflow-y: auto; padding: 28px 16px 40px; border-right: 1px solid var(--line); font-family: var(--sans); font-size: 13.5px; }
nav.toc .book { display: block; font-weight: 700; font-size: 14px; color: var(--fg); border: 0; margin-bottom: 14px; line-height: 1.3; }
nav.toc .eyebrow { margin-bottom: 6px; }
nav.toc ol { list-style: none; padding: 0; margin: 0; }
nav.toc li { margin: 1px 0; }
nav.toc a { display: block; padding: 3px 8px; border-radius: 4px; border: 0; color: var(--fg2); }
nav.toc a:hover { background: var(--code-bg); color: var(--accent2); }
nav.toc li.cur a { background: var(--thm); color: var(--accent2); font-weight: 600; }
nav.toc .num { color: var(--muted); font-variant-numeric: tabular-nums; margin-right: 6px; display: inline-block; width: 1.4em; }
main { padding: 28px 40px 80px; max-width: 760px; }
.eyebrow { font-family: var(--sans); font-size: 12px; letter-spacing: 1.2px; text-transform: uppercase; color: var(--muted); font-weight: 700; margin: 0 0 4px; }
h1 { font-family: var(--serif); font-size: 32px; font-weight: 600; margin: 4px 0 8px; line-height: 1.2; letter-spacing: -0.01em; }
h2 { font-family: var(--serif); font-size: 24px; font-weight: 600; margin: 40px 0 10px; padding-top: 8px; border-top: 1px solid var(--line); letter-spacing: -0.005em; }
h3 { font-family: var(--serif); font-size: 20px; font-weight: 600; margin: 28px 0 6px; }
h4 { font-family: var(--sans); font-size: 14px; text-transform: uppercase; letter-spacing: 0.6px; margin: 18px 0 4px; color: var(--fg2); }
.sub { font-size: 16px; color: var(--muted); margin: 0 0 8px; }
p { margin: 8px 0 14px; }
ul, ol { padding-left: 1.4em; }
li { margin: 4px 0; }
code, .term, var { background: var(--code-bg); padding: 1px 5px; border-radius: 3px; font-size: 0.82em; font-family: var(--mono); color: var(--code-fg); font-style: normal; }
pre { background: var(--code-bg); border: 1px solid var(--line); border-radius: 6px; padding: 12px 14px; overflow-x: auto; font-size: 13.5px; line-height: 1.5; font-family: var(--mono); }
pre code { background: none; padding: 0; font-size: inherit; }
.math { font-family: var(--math); font-size: 1.02em; }
.disp { display: block; text-align: center; margin: 12px 0 16px; font-size: 1.1em; }
a { color: var(--accent); text-decoration: none; border-bottom: 1px solid #c9dcf3; }
a:hover { color: var(--accent2); border-bottom-color: var(--accent2); }
em { color: var(--fg2); }
strong { font-weight: 700; }
table { width: 100%; border-collapse: collapse; margin: 10px 0 18px; font-size: 15.5px; }
th, td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { background: var(--code-bg); font-family: var(--sans); font-weight: 700; font-size: 12px; letter-spacing: 0.5px; color: var(--muted); text-transform: uppercase; }
.card { background: var(--card); border: 1px solid var(--line); border-left: 3px solid var(--fg2); padding: 12px 18px; border-radius: 6px; margin: 14px 0 18px; font-size: 16.5px; }
.card .label { font-family: var(--sans); font-size: 11px; letter-spacing: 1.2px; text-transform: uppercase; color: var(--muted); font-weight: 700; display: block; margin-bottom: 4px; }
.card p { margin: 6px 0; }
.thm { background: var(--thm); border-color: var(--thm-line); border-left-color: var(--accent); }
.olai { background: var(--olai); border-color: var(--olai-line); border-left-color: #2f9e5f; color: var(--olai-fg); }
.olai code { background: rgba(0,0,0,0.06); color: inherit; }
.warn { background: var(--warn); border-color: var(--warn-line); border-left-color: #d9962a; color: var(--warn-fg); }
.hs { background: var(--hs); border-color: var(--hs-line); border-left-color: #7c5cc4; color: var(--hs-fg); }
.hs code { background: rgba(0,0,0,0.06); color: inherit; }
.ex { border-left-color: #d1508f; }
.two { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
figure { margin: 18px 0 22px; text-align: center; }
figure svg { max-width: 100%; height: auto; }
figcaption { font-family: var(--sans); font-size: 13px; color: var(--muted); margin-top: 6px; }
.small, .cite { font-size: 14px; color: var(--muted); }
footer { margin-top: 40px; padding: 14px 18px; background: var(--code-bg); border: 1px solid var(--line); border-radius: 6px; font-size: 15px; color: var(--muted); }
.pn { display: flex; justify-content: space-between; gap: 16px; font-family: var(--sans); font-size: 13.5px; margin: 0 0 18px; }
main > .pn:last-child { margin: 40px 0 0; padding-top: 14px; border-top: 1px solid var(--line); }
.pn a { border: 0; color: var(--accent); }
.pn a:hover { color: var(--accent2); text-decoration: underline; }
svg text { font-family: var(--sans); fill: var(--fg); }
svg .box { fill: var(--card); stroke: var(--fg2); stroke-width: 1.4; }
svg .edge { stroke: var(--fg2); stroke-width: 1.4; fill: none; marker-end: url(#arr); }
svg .lbl { font-size: 11.5px; fill: var(--muted); }
svg .orch { stroke-dasharray: 4 3; }
@media (max-width: 900px) {
  .layout { grid-template-columns: 1fr; }
  nav.toc { position: static; height: auto; border-right: 0; border-bottom: 1px solid var(--line); }
  main { padding: 20px 16px 60px; }
  .two { grid-template-columns: 1fr; }
  body { font-size: 17px; }
}
/* plain-English gloss under a formula or definition */
.gloss { font-family: var(--sans); font-size: 15px; color: var(--fg2); margin: 6px 0 12px; padding-left: 12px; border-left: 2px solid var(--line); }
.card .gloss { border-left-color: rgba(0,0,0,0.12); }
/* external reference links (nLab, Wikipedia, MDN, …): first occurrence of a term on each page */
a.ext { color: var(--accent); border-bottom: 1px dotted var(--accent); }
a.ext::after { content: "\2197"; font-size: 0.65em; vertical-align: super; margin-left: 1px; color: var(--muted); }
a.ext:hover { border-bottom-style: solid; }