:root {
  --fg: #1a1a1a;
  --muted: #555;
  --accent: #1877f2;
  --bg: #f5f6f8;
  --card: #fff;
  --border: #e3e5e8;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Roboto, Helvetica, Arial, sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.75;
}
header {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 34px 20px;
  text-align: center;
}
header h1 { margin: 0; font-size: 1.6rem; }
header .sub { color: var(--muted); margin: 6px 0 0; font-size: .95rem; }
main {
  max-width: 820px;
  margin: 28px auto;
  padding: 0 20px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 32px 36px;
  margin-bottom: 24px;
}
h2 { font-size: 1.3rem; margin-top: 0; }
h3 { font-size: 1.05rem; margin-bottom: 4px; margin-top: 22px; }
.lang {
  font-size: .8rem;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: .05em;
  margin-bottom: 18px;
  border-top: 1px dashed var(--border);
  padding-top: 26px;
}
.lang:first-of-type { border-top: none; padding-top: 0; }
ul, ol { padding-left: 22px; }
li { margin: 6px 0; }
a { color: var(--accent); }
.box {
  background: #eef4ff;
  border: 1px solid #cddffd;
  border-radius: 8px;
  padding: 16px 20px;
  margin: 14px 0;
}
.box ol { margin: 8px 0; }
footer {
  text-align: center;
  color: var(--muted);
  font-size: .85rem;
  padding: 30px 20px 50px;
}
nav.links a { display: inline-block; margin: 8px 0; }
.updated { color: var(--muted); font-size: .85rem; margin-bottom: 18px; }
strong { color: #000; }