:root {
  color-scheme: light dark;
  --ground: #F7F8F9;
  --surface: #FFFFFF;
  --surface-alt: #EEF1F4;
  --ink: #1B2A3A;
  --ink-muted: #5C6B7A;
  --primary: #2C5F8A;
  --hairline: #DDE3E8;
  --radius: 8px;
  --font: -apple-system, BlinkMacSystemFont, system-ui, Roboto, "Segoe UI", "Helvetica Neue", Arial, sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ground: #12171C;
    --surface: #1A2027;
    --surface-alt: #232B33;
    --ink: #E8EDF1;
    --ink-muted: #94A3B0;
    --primary: #5FA3D6;
    --hairline: #2C353E;
  }
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--ground);
  color: var(--ink);
  font: 400 1rem/1.6 var(--font);
  font-variant-numeric: tabular-nums;
  -webkit-font-smoothing: antialiased;
}

.wrap { width: 100%; max-width: 46rem; margin-inline: auto; padding-inline: 1rem; }

a { color: var(--primary); text-decoration-thickness: 1px; text-underline-offset: 0.18em; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 2px solid var(--primary); outline-offset: 2px; border-radius: 2px; }

.mark { display: block; flex: none; }

/* Masthead */
.masthead { background: var(--surface); border-bottom: 1px solid var(--hairline); }
.masthead .wrap {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem 1.5rem;
  padding-block: 0.875rem;
}
.brand { display: inline-flex; align-items: center; gap: 0.75rem; color: inherit; text-decoration: none; }
.brand-name { display: block; font-size: 1.0625rem; font-weight: 600; letter-spacing: -0.01em; line-height: 1.25; }
.brand-caption { display: block; font-size: 0.8125rem; line-height: 1.35; color: var(--ink-muted); }
.doc-nav { display: flex; gap: 1.25rem; font-size: 0.9375rem; }
.doc-nav a { color: var(--ink-muted); text-decoration: none; padding-block: 0.25rem; border-bottom: 2px solid transparent; }
.doc-nav a:hover { color: var(--ink); }
.doc-nav a[aria-current="page"] { color: var(--ink); font-weight: 600; border-bottom-color: var(--primary); }

/* Document */
main { padding-block: 2rem 1.5rem; }
.sheet { background: var(--surface); border: 1px solid var(--hairline); border-radius: var(--radius); padding: 2.5rem 2.75rem 2rem; }
.doc-head { margin-bottom: 1.75rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--hairline); }
h1 { margin: 0 0 0.375rem; font-size: 2rem; font-weight: 600; line-height: 1.2; letter-spacing: -0.02em; }
.updated { margin: 0; font-size: 0.875rem; color: var(--ink-muted); }

.doc-body > :first-child { margin-top: 0; }
.doc-body h2 {
  margin: 2.25rem 0 0.75rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--hairline);
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -0.01em;
  scroll-margin-top: 1rem;
}
.doc-body h3 { margin: 1.75rem 0 0.5rem; font-size: 1rem; font-weight: 600; line-height: 1.4; }
.doc-body p, .doc-body ul { margin: 0 0 1rem; }
.doc-body ul { padding-left: 1.25rem; }
.doc-body li { margin-bottom: 0.375rem; padding-left: 0.25rem; }
.doc-body li::marker { color: var(--ink-muted); }
.doc-body strong { font-weight: 600; }

.doc-body blockquote {
  position: relative;
  overflow: hidden;
  margin: 1.5rem 0;
  padding: 1.25rem 1.5rem 1.25rem 1.75rem;
  background: var(--surface-alt);
  border-radius: var(--radius);
}
.doc-body blockquote::before { content: ""; position: absolute; inset: 0 auto 0 0; width: 3px; background: var(--primary); }
.doc-body blockquote > :last-child { margin-bottom: 0; }
.doc-body blockquote p:first-child { margin-bottom: 0.5rem; }

.toc { margin: 2rem 0 0; }
.toc-title { margin: 0 0 0.25rem; font-size: 0.75rem; font-weight: 600; letter-spacing: 0.06em; text-transform: uppercase; color: var(--ink-muted); }
.toc ol { margin: 0; padding: 0; list-style: none; columns: 2 15rem; column-gap: 2rem; font-size: 0.9375rem; }
.toc li { break-inside: avoid; margin: 0; padding: 0.375rem 0; border-bottom: 1px solid var(--hairline); }
.toc a { color: var(--ink); text-decoration: none; }
.toc a:hover { color: var(--primary); text-decoration: underline; }

/* Index */
.hero { padding-block: 3rem 2rem; text-align: center; }
.hero .mark { margin: 0 auto 1.375rem; }
.hero h1 { margin: 0; font-size: 1.375rem; letter-spacing: -0.01em; }
.rule { width: 52px; height: 1px; margin: 0.875rem auto; border: 0; background: var(--hairline); }
.hero p { margin: 0; font-size: 0.8125rem; color: var(--ink-muted); }
.doc-links { display: grid; grid-template-columns: repeat(auto-fit, minmax(15rem, 1fr)); gap: 0.75rem; margin: 0; padding: 0; list-style: none; }
.doc-link {
  display: block;
  height: 100%;
  padding: 1.25rem 1.5rem;
  background: var(--surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius);
  color: inherit;
  text-decoration: none;
}
.doc-link:hover { border-color: var(--primary); }
.doc-link strong { display: block; margin-bottom: 0.25rem; font-size: 1.0625rem; font-weight: 600; color: var(--primary); }
.doc-link span { font-size: 0.9375rem; color: var(--ink-muted); }

/* Footer */
.site-foot {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.25rem 1.5rem;
  padding-block: 0.5rem 2.5rem;
  font-size: 0.8125rem;
  color: var(--ink-muted);
}
.site-foot a { color: var(--ink-muted); }

@media (max-width: 40rem) {
  main { padding-block: 1rem 1rem; }
  .sheet { padding: 1.5rem 1.25rem 1.25rem; }
  h1 { font-size: 1.625rem; }
  .doc-body h2 { margin-top: 1.75rem; padding-top: 1.5rem; }
  .doc-body blockquote { padding: 1rem 1.125rem 1rem 1.375rem; }
}

@media print {
  .masthead, .toc { display: none; }
  body { background: #FFFFFF; color: #000000; }
  .sheet { border: 0; padding: 0; }
  a { color: inherit; }
}