:root {
  --indigo: #2a2d79;
  --teal: #09716a;
  --text: #242424;
  --muted: #5d5d5d;
  --line: #e2e4ee;
  --paper: #f5f6fa;
  --bg: #ffffff;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--text);
  background: var(--bg);
  font: 18px/1.55 system-ui, -apple-system, "Segoe UI", sans-serif;
}

a { color: var(--teal); }
a:hover { color: var(--indigo); }

.skip {
  position: absolute;
  left: 0.5rem;
  top: -3rem;
  background: var(--indigo);
  color: white;
  padding: 0.4rem 0.7rem;
}
.skip:focus { top: 0.5rem; color: white; }

.site-header {
  background: var(--indigo);
  color: white;
}

.site-header a { color: white; text-decoration: none; }

.header-inner,
.site-footer .footer-inner,
main {
  width: min(46rem, calc(100% - 2rem));
  margin: 0 auto;
}

.header-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem 1.5rem;
  padding: 0.85rem 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  font-size: 1.25rem;
}

.mark {
  width: 1.35rem;
  height: 1.35rem;
  display: block;
}

.site-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 1rem;
}

.site-nav a {
  color: #efeef8;
  font-size: 0.95rem;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: white;
  text-decoration: underline;
  text-underline-offset: 0.25rem;
}

main { padding: 2rem 0 3.5rem; }

main h1, main h2, main h3 { line-height: 1.25; color: var(--indigo); }
main h1 { font-size: 1.8rem; margin: 0 0 0.8rem; }
main h2 { font-size: 1.3rem; margin: 1.8rem 0 0.5rem; }
main h3 { font-size: 1.1rem; margin: 1.4rem 0 0.4rem; }

main img { max-width: 100%; height: auto; }

main pre {
  background: var(--paper);
  border: 1px solid var(--line);
  padding: 0.85rem 1rem;
  overflow: auto;
  font-size: 0.9rem;
}

main code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.92em;
}

main table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.95rem;
}
main th, main td {
  border-bottom: 1px solid var(--line);
  padding: 0.4rem 0.55rem;
  text-align: left;
  vertical-align: top;
}

.lede {
  font-size: 1.2rem;
  margin-top: 0;
}

.home-intro {
  background: var(--paper);
  margin: -2rem 0 0.4rem;
  padding: 1.5rem 0 1.15rem;
  box-shadow: 0 0 0 100vmax var(--paper);
  clip-path: inset(0 -100vmax);
}
.home-intro::after {
  content: "";
  display: block;
  width: 4.5rem;
  height: 3px;
  margin-top: 1.15rem;
  background: var(--indigo);
}
.home-lead {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}
.home-lead h1 { margin-top: 0; }
.home-lead p:last-child { margin-bottom: 0; }
.home-mark {
  width: 13.75rem;
  height: auto;
  flex: none;
}
@media (max-width: 40rem) {
  .home-lead {
    flex-direction: column-reverse;
    align-items: flex-start;
  }
  .home-mark { width: min(13.75rem, 70%); }
}

.doors { list-style: none; padding: 0; margin: 1.5rem 0 0; }
.doors li {
  border-top: 1px solid var(--line);
  padding: 0.85rem 0;
}
.doors li:last-child { border-bottom: 1px solid var(--line); }
.doors a { font-weight: 650; text-decoration: none; }
.doors a:hover { text-decoration: underline; }
.doors span { display: block; color: var(--muted); }

.meta, .kicker, .notice { color: var(--muted); }
.meta { margin: 0 0 0.4rem; }
.kicker { margin: 0 0 0.6rem; font-size: 0.95rem; }
.notice {
  background: var(--paper);
  border-left: 3px solid var(--teal);
  padding: 0.6rem 0.8rem;
  margin: 0 0 1.2rem;
}

.listing { list-style: none; padding: 0; margin: 1rem 0 0; }
.listing li {
  border-top: 1px solid var(--line);
  padding: 0.7rem 0;
}
.listing time, .listing .forum-name { color: var(--muted); font-size: 0.9rem; }
.listing a { text-decoration: none; font-weight: 600; }
.listing a:hover { text-decoration: underline; }

.site-footer {
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.95rem;
}
.site-footer .footer-inner { padding: 1.2rem 0 2rem; }
.site-footer a { color: var(--indigo); }

.video { margin: 1.4rem 0 0; }
.video iframe {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: 0;
  background: #111;
}
.video figcaption { margin-top: 0.45rem; }

.unit-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 0.8rem;
  border-top: 1px solid var(--line);
}
.unit-nav .next { text-align: right; }

.course-outline { padding-left: 1.2rem; }
.course-outline li { margin: 0.2rem 0; }