:root {
  color-scheme: light;
  --ink: #111;
  --muted: #66615a;
  --paper: #f6f4ef;
  --sheet: #fffdf8;
  --line: #d8d2c7;
  --soft: #ece7dc;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: ui-serif, Georgia, "Times New Roman", "Songti SC", serif;
  line-height: 1.55;
}

a {
  color: inherit;
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
}

.page {
  min-height: 100vh;
  padding: 28px;
}

.shell {
  max-width: 980px;
  margin: 0 auto;
}

.nav,
.footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 13px;
  letter-spacing: 0.02em;
}

.brand {
  font-weight: 650;
  text-decoration: none;
}

.brand,
.footer-brand {
  display: inline-flex;
  align-items: center;
}

.logo-mark {
  display: block;
  width: 126px;
  height: auto;
}

.footer-brand .logo-mark {
  width: 120px;
}

.nav-links,
.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}

.hero {
  padding: 94px 0 70px;
}

.hero h1,
.doc h1 {
  margin: 0;
  font-size: clamp(48px, 9vw, 104px);
  line-height: 0.92;
  letter-spacing: 0;
  font-weight: 500;
}

.hero .lead {
  max-width: 690px;
  margin: 26px 0 0;
  font-size: clamp(26px, 4vw, 46px);
  line-height: 1.05;
}

.zh-line,
.subline,
.doc .meta {
  max-width: 640px;
  color: var(--muted);
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

.zh-line {
  margin: 20px 0 0;
  font-size: 19px;
}

.subline {
  margin: 30px 0 0;
  font-size: 17px;
}

.actions {
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  border: 1px solid var(--ink);
  border-radius: 999px;
  background: var(--ink);
  color: #fff;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 14px;
  text-decoration: none;
}

.features {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.feature,
.doc-card {
  background: var(--sheet);
  padding: 24px;
}

.feature h2,
.doc h2 {
  margin: 0 0 12px;
  font-size: 20px;
  line-height: 1.15;
  font-weight: 520;
}

.feature p,
.doc p,
.doc li {
  margin: 0;
  color: var(--muted);
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 15px;
}

.doc {
  padding: 72px 0;
}

.doc h1 {
  font-size: clamp(42px, 7vw, 76px);
}

.doc .meta {
  margin: 18px 0 34px;
}

.doc-grid {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.doc-card p + p,
.doc-card ul {
  margin-top: 14px;
}

.doc-card ul {
  padding-left: 20px;
}

.footer {
  padding: 44px 0 10px;
  border-top: 1px solid var(--line);
  margin-top: 64px;
}

@media (max-width: 760px) {
  .page {
    padding: 20px;
  }

  .nav,
  .footer {
    align-items: flex-start;
    flex-direction: column;
  }

  .hero {
    padding: 70px 0 52px;
  }

  .features {
    grid-template-columns: 1fr;
  }
}