:root {
  color-scheme: light;
  --bg: #f7f5ef;
  --paper: #fffdf8;
  --ink: #1f2933;
  --muted: #687381;
  --line: #ddd7ca;
  --brand: #0ea5e9;
  --brand-strong: #0284c7;
  --accent: #8b5cf6;
  --soft: #eef4f8;
  --warn: #8b5e1a;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background:
    linear-gradient(135deg, rgba(14,165,233,0.06), transparent 32rem),
    linear-gradient(315deg, rgba(139,92,246,0.06), transparent 28rem),
    var(--bg);
  color: var(--ink);
  font-family: "Noto Sans SC","Microsoft YaHei","PingFang SC",system-ui,-apple-system,sans-serif;
  line-height: 1.75;
}

a { color: var(--brand); text-decoration-thickness: from-font; text-underline-offset: 0.2em; }
a:hover { color: var(--brand-strong); }

.page { margin: 0 auto; max-width: 1120px; padding: 40px 24px 64px; }

.topbar {
  align-items: center; display: flex; gap: 20px;
  justify-content: space-between; padding: 8px 0 28px;
}
.brand { color: var(--brand-strong); font-size: 18px; font-weight: 800; display: flex; align-items: center; gap: 8px; }
.brand i { color: var(--brand); }
.nav { display: flex; flex-wrap: wrap; gap: 14px; justify-content: flex-end; }
.nav a {
  border: 1px solid rgba(14,165,233,0.22); border-radius: 999px;
  font-size: 14px; font-weight: 700; min-height: 40px; padding: 7px 14px;
  text-decoration: none; transition: background 160ms, border-color 160ms, color 160ms;
}
.nav a:hover, .nav a[aria-current="page"] {
  background: var(--soft); border-color: rgba(14,165,233,0.42); color: var(--brand-strong);
}

.hero { border-bottom: 1px solid var(--line); padding: 24px 0 28px; }
.eyebrow { color: var(--accent); font-size: 14px; font-weight: 800; margin: 0 0 10px; }
h1 { color: var(--ink); font-size: clamp(32px,5vw,56px); line-height: 1.12; margin: 0; }
.summary { color: var(--muted); font-size: 18px; margin: 18px 0 0; max-width: 780px; }
.meta { color: var(--muted); display: flex; flex-wrap: wrap; font-size: 14px; gap: 12px; margin-top: 18px; }

.layout { display: grid; gap: 40px; grid-template-columns: minmax(0,1fr) 260px; padding-top: 36px; }

article {
  background: rgba(255,253,248,0.88); border: 1px solid rgba(221,215,202,0.86);
  border-radius: 8px; box-shadow: 0 18px 45px rgba(31,41,51,0.08);
  padding: clamp(22px,4vw,44px);
}
aside { align-self: start; position: sticky; top: 24px; }
.toc {
  background: rgba(255,253,248,0.76); border: 1px solid rgba(221,215,202,0.86);
  border-radius: 8px; padding: 18px;
}
.toc-title { color: var(--ink); font-size: 14px; font-weight: 800; margin: 0 0 10px; }
.toc a { color: var(--muted); display: block; font-size: 14px; padding: 6px 0; text-decoration: none; }
.toc a:hover { color: var(--brand-strong); }

section { border-top: 1px solid var(--line); padding-top: 28px; }
section:first-child { border-top: 0; padding-top: 0; }
section + section { margin-top: 30px; }

h2 { color: var(--ink); font-size: 24px; line-height: 1.35; margin: 0 0 14px; }
h3 { color: var(--ink); font-size: 18px; margin: 22px 0 8px; }
p, li { color: #344150; font-size: 16px; }
p { margin: 0 0 14px; }
ul { margin: 0 0 16px; padding-left: 1.25em; }
li + li { margin-top: 8px; }

.notice {
  background: #fff7e6; border: 1px solid rgba(139,94,26,0.22);
  border-radius: 8px; color: var(--warn); margin: 22px 0; padding: 16px 18px;
}
.notice strong { color: #70470f; }

.footer {
  border-top: 1px solid var(--line); color: var(--muted);
  font-size: 14px; margin-top: 36px; padding-top: 24px;
}

.back-link {
  display: inline-flex; align-items: center; gap: 6px;
  color: var(--brand); font-size: 14px; font-weight: 600;
  text-decoration: none; margin-bottom: 16px;
}
.back-link:hover { color: var(--brand-strong); }

@media (max-width: 860px) {
  .page { padding: 24px 16px 44px; }
  .topbar { align-items: flex-start; flex-direction: column; }
  .nav { justify-content: flex-start; }
  .layout { display: block; padding-top: 24px; }
  aside { margin: 0 0 20px; position: static; }
  article { padding: 22px 18px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: 0.01ms !important; }
}