:root {
  --bg: #f5f6f8;
  --ink: #1a1d24;
  --muted: #5c6570;
  --accent: #1f4b7a;
  --card: #ffffff;
  --line: #d8dde3;
  --max: 820px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.75;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 28px 20px 64px;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-bottom: 18px;
}
.brand strong {
  font-family: "Noto Serif SC", "Songti SC", serif;
  font-size: 22px;
  letter-spacing: 0.06em;
}
.brand span {
  color: var(--muted);
  font-size: 13px;
}

nav.links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 18px;
  margin-bottom: 28px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}
nav.links a { color: var(--ink); }
nav.links a:hover { color: var(--accent); text-decoration: none; }

article {
  background: var(--card);
  border: 1px solid var(--line);
  padding: 32px 28px 40px;
}

h1 {
  margin: 0 0 8px;
  font-family: "Noto Serif SC", "Songti SC", serif;
  font-size: 28px;
  line-height: 1.3;
}
.meta {
  color: var(--muted);
  font-size: 13px;
  margin-bottom: 24px;
}

h2 {
  margin: 28px 0 10px;
  font-size: 18px;
  padding-top: 8px;
  border-top: 1px solid var(--line);
}
h2:first-of-type { border-top: 0; padding-top: 0; }

h3 {
  margin: 20px 0 8px;
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
}

h4 {
  margin: 14px 0 6px;
  font-size: 15px;
  font-weight: 700;
  color: #2c333c;
}

p, li { font-size: 15px; color: #2c333c; }
ul, ol { padding-left: 1.3em; }
li { margin: 6px 0; }

.toc {
  background: #f7f9fb;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px 18px;
  margin: 16px 0 24px;
}
.toc ol { margin: 8px 0 0; }

.sdk {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px 16px;
  margin: 12px 0;
  background: #fafbfc;
}
.sdk h4 { margin-top: 0; }
.sdk dl {
  margin: 0;
  display: grid;
  grid-template-columns: 6.5em 1fr;
  gap: 6px 10px;
  font-size: 14px;
}
.sdk dt {
  color: var(--muted);
  font-weight: 600;
}
.sdk dd {
  margin: 0;
  color: #2c333c;
}

.callout {
  margin: 14px 0;
  padding: 14px 16px;
  background: #fff8ef;
  border: 1px solid #ecd9b8;
  border-radius: 8px;
}
.callout strong { color: #8a5a12; }

.note {
  margin-top: 28px;
  padding: 14px 16px;
  background: #f0f3f7;
  border-left: 3px solid var(--accent);
  color: var(--muted);
  font-size: 13px;
}

footer {
  margin-top: 28px;
  color: var(--muted);
  font-size: 12px;
  text-align: center;
}
footer .beian {
  margin-top: 8px;
}
footer .beian a {
  color: var(--muted);
}
footer .beian a:hover { color: var(--accent); }

@media (max-width: 640px) {
  article { padding: 22px 16px 28px; }
  h1 { font-size: 24px; }
}