:root {
  color-scheme: light;
  --paper: #f8faf8;
  --surface: #ffffff;
  --ink: #183039;
  --muted: #52686d;
  --line: #c7d8d4;
  --teal: #286f68;
  --wash: #e7f1ec;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  line-height: 1.75;
}
a { color: var(--teal); text-underline-offset: .2em; }
a:hover { color: var(--ink); }
a:focus-visible { outline: 3px solid var(--teal); outline-offset: 4px; border-radius: 2px; }
.skip { position: absolute; top: -5rem; left: 1rem; background: var(--surface); padding: .5rem 1rem; z-index: 10; }
.skip:focus { top: 1rem; }
.shell { width: min(100% - 3rem, 68rem); margin-inline: auto; }
.site-header { border-bottom: 1px solid var(--line); background: var(--surface); }
.header-inner { min-height: 5rem; display: flex; align-items: center; justify-content: space-between; gap: 2rem; }
.brand { color: var(--ink); font-weight: 760; letter-spacing: -.035em; text-decoration: none; font-size: 1.15rem; }
.site-nav { display: flex; flex-wrap: wrap; gap: 1.5rem; font-size: .92rem; }
.site-nav a { color: var(--muted); text-decoration: none; }
.site-nav a[aria-current="page"] { color: var(--ink); font-weight: 700; text-decoration: underline; text-decoration-color: var(--teal); text-decoration-thickness: 2px; }
.hero { padding: clamp(4rem, 9vw, 8rem) 0 clamp(4rem, 8vw, 7rem); }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.3fr) minmax(15rem, .7fr); align-items: end; gap: clamp(2rem, 7vw, 7rem); }
.kicker { display: inline-block; margin: 0 0 1.2rem; border-left: 3px solid var(--teal); padding-left: .8rem; color: var(--muted); font-size: .88rem; }
h1, h2, h3 { line-height: 1.25; letter-spacing: -.035em; }
h1 { margin: 0 0 1.4rem; max-width: 14ch; font-size: clamp(2.6rem, 6.3vw, 5rem); font-weight: 760; }
h2 { margin: 0 0 1.2rem; font-size: clamp(1.5rem, 3vw, 2.05rem); }
h3 { margin: 0 0 .45rem; font-size: 1.08rem; }
.lede { margin: 0; max-width: 36rem; color: var(--muted); font-size: clamp(1.05rem, 1.8vw, 1.25rem); }
.identity { border-top: 2px solid var(--teal); padding-top: 1.15rem; color: var(--muted); font-size: .94rem; }
.identity strong { display: block; color: var(--ink); font-size: 1rem; margin-bottom: .5rem; }
.identity p { margin: 0; }
.band { background: var(--wash); border-block: 1px solid var(--line); }
.band-inner { padding-block: clamp(2.5rem, 5vw, 4.5rem); }
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: clamp(1.5rem, 4vw, 4rem); }
.step { border-top: 1px solid var(--teal); padding-top: 1.2rem; }
.step p { margin: 0; color: var(--muted); }
.links { padding-block: clamp(3rem, 6vw, 5rem); }
.link-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1rem; }
.link-card { display: block; border: 1px solid var(--line); background: var(--surface); padding: 1.5rem; text-decoration: none; transition: border-color .15s ease; }
.link-card:hover { border-color: var(--teal); }
.link-card strong { display: block; color: var(--ink); font-size: 1.1rem; margin-bottom: .3rem; }
.link-card span { color: var(--muted); font-size: .94rem; }
.document { width: min(100% - 3rem, 48rem); margin-inline: auto; padding-block: clamp(3.5rem, 7vw, 6rem); }
.document h1 { max-width: none; font-size: clamp(2.3rem, 5vw, 3.75rem); }
.document .intro { color: var(--muted); font-size: 1.07rem; margin: 0 0 3rem; }
.document section { padding: 1.6rem 0; border-top: 1px solid var(--line); }
.document section p { margin: .6rem 0 0; }
.document section ul { padding-left: 1.4rem; margin-bottom: 0; }
.meta { color: var(--muted); font-size: .9rem; }
.site-footer { border-top: 1px solid var(--line); background: var(--surface); }
.footer-inner { padding-block: 2rem; display: flex; justify-content: space-between; flex-wrap: wrap; gap: 1rem; color: var(--muted); font-size: .88rem; }
.footer-inner p { margin: 0; }
.footer-inner nav { display: flex; gap: 1.2rem; flex-wrap: wrap; }
@media (max-width: 700px) {
  .header-inner { align-items: flex-start; flex-direction: column; justify-content: center; gap: .3rem; padding-block: 1rem; }
  .hero-grid, .steps, .link-grid { grid-template-columns: 1fr; }
  .identity { max-width: 30rem; }
  .site-nav { gap: .9rem; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .link-card { transition: none; }
}