:root {
  color-scheme: light dark;
  --bg: #f7fafa; --surface: #ffffff; --text: #17262e; --muted: #4a5c66;
  --head: #1d4a52; --link: #145a66; --link-hover: #0c3a42; --rule: #c9d8da;
  --code-bg: #e8efef; --accent: #c4502f; --note-bg: #e6f2f0;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #11181b; --surface: #182226; --text: #e2eaec; --muted: #a8b8bd;
    --head: #9fd6ce; --link: #7fd0c4; --link-hover: #b5ebe3; --rule: #2d3d42;
    --code-bg: #1f2c31; --accent: #ef8f72; --note-bg: #1a2c2e;
  }
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--text); font: 17px/1.65 system-ui, -apple-system, "Segoe UI", sans-serif; }
a { color: var(--link); text-underline-offset: 3px; }
a:hover { color: var(--link-hover); }
a:focus-visible, summary:focus-visible { outline: 3px solid var(--link); outline-offset: 3px; }
header, footer { max-width: 1240px; margin: auto; padding: 18px 24px; }
header { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 20px; border-bottom: 1px solid var(--rule); }
.tagline { color: var(--muted); font-size: .95rem; }
.shell { max-width: 1240px; margin: auto; display: grid; grid-template-columns: 250px minmax(0, 1fr); gap: 32px; padding: 0 24px; }
main { min-width: 0; padding: 8px 0 32px; }
.side { position: sticky; top: 0; align-self: start; max-height: 100vh; overflow-y: auto; padding: 18px 0; font-size: .95rem; }
.side ul, .side-mobile ul { list-style: none; margin: 0 0 10px; padding: 0; }
.side li, .side-mobile li { margin: 2px 0; }
.side a, .side-mobile a { display: block; padding: 3px 10px; border-left: 3px solid transparent; text-decoration: none; }
.side a[aria-current=page], .side-mobile a[aria-current=page] { border-left-color: var(--accent); font-weight: 700; color: var(--head); }
.group { margin: 14px 0 4px; font-size: .78rem; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
.side-mobile { display: none; }
.brand { display: flex; align-items: center; gap: 14px; font-weight: 700; font-size: 1.35rem; text-decoration: none; color: var(--head); }
.brand img { width: 48px; height: 48px; }
h1, h2, h3 { line-height: 1.25; color: var(--head); }
h1 { font-size: clamp(1.9rem, 5vw, 2.8rem); }
p, li { max-width: 80ch; }
pre { overflow-x: auto; padding: 16px; background: var(--code-bg); border-radius: 8px; }
code { font-size: .9em; }
table { display: block; overflow-x: auto; border-collapse: collapse; width: 100%; font-size: .93rem; }
td, th { padding: 9px 10px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--rule); }
blockquote { margin: 1em 0; padding: 10px 18px; border-left: 4px solid var(--head); background: var(--note-bg); }
details { margin: .8em 0; }
summary { cursor: pointer; }
img { max-width: 100%; height: auto; }
footer { border-top: 1px solid var(--rule); font-size: .9rem; color: var(--muted); }
.skip { position: absolute; top: -100px; left: 12px; padding: 8px; background: var(--surface); }
.skip:focus { top: 8px; }
.hero { padding: 8px 0 4px; }
.eyebrow { color: var(--muted); font-size: .95rem; letter-spacing: .02em; margin: 0; }
.lead { font-size: 1.15rem; }
.banner { display: block; width: 100%; max-width: 640px; border-radius: 18px; margin: 8px 0 12px; }
.boundary { border-left: 5px solid var(--accent); padding: 12px 20px; background: var(--note-bg); border-radius: 0 8px 8px 0; }
.actions { display: flex; flex-wrap: wrap; gap: 10px; }
.button { display: inline-block; padding: 9px 16px; border-radius: 8px; background: var(--head); color: var(--bg); text-decoration: none; font-weight: 600; }
.button:hover { color: var(--bg); opacity: .9; }
.button.secondary { background: transparent; color: var(--link); border: 2px solid var(--link); }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 14px; margin: 1em 0; }
.card { background: var(--surface); border: 1px solid var(--rule); border-radius: 10px; padding: 14px 16px; }
.card h4 { margin: 0 0 6px; font-size: 1.05rem; }
.card p { margin: 0; font-size: .95rem; }
@media (max-width: 860px) {
  .shell { display: block; padding: 0 16px; }
  .side { display: none; }
  .side-mobile { display: block; margin: 12px 0; padding: 8px 12px; border: 1px solid var(--rule); border-radius: 8px; background: var(--surface); }
  .side-mobile summary { font-weight: 700; }
  header, footer { padding: 14px 16px; }
  td, th { padding: 7px; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; transition: none !important; } }
/* Typeset TeX statements (see math.js) */
.tex-statement { margin: .6em 0 .2em; padding: .6em .9em; border-left: 3px solid var(--head); overflow-x: auto; line-height: 1.6; }
details.tex-source { margin: 0 0 1em; font-size: .85em; }
details.tex-source > summary { opacity: .8; }
mjx-container[display="true"] { overflow-x: auto; overflow-y: hidden; max-width: 100%; }