:root {
  --bg: #f4f9fd;
  --card: #ffffff;
  --text: #1f2a35;
  --muted: #64717e;
  --accent: #2b8ad6;
  --line: #dce7f1;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1720;
    --card: #16212c;
    --text: #e6eef6;
    --muted: #93a3b3;
    --accent: #7cc4ff;
    --line: #253342;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;
}
main { max-width: 760px; margin: 0 auto; padding: 48px 20px 64px; }
header { margin-bottom: 32px; }
.brand { display: flex; align-items: center; gap: 14px; }
.logo { width: 72px; height: 72px; flex: none; display: block; }
.logo img { width: 72px; height: 72px; border-radius: 16px; display: block; box-shadow: 0 4px 14px rgba(40, 90, 140, 0.18); }
h1 { font-size: 30px; line-height: 1.25; margin: 0; }
.subtitle { color: var(--muted); margin: 4px 0 0; }
h2 { font-size: 20px; margin: 36px 0 8px; }
h3 { font-size: 17px; margin: 24px 0 6px; }
p, li { color: var(--text); }
ul { padding-left: 1.3em; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.card {
  background: var(--card); border: 1px solid var(--line);
  border-radius: 14px; padding: 20px 22px; margin: 16px 0;
}
.lang-switch { margin: 0 0 8px; font-size: 14px; color: var(--muted); }
.meta { color: var(--muted); font-size: 14px; }
section + section { border-top: 1px solid var(--line); margin-top: 48px; padding-top: 8px; }
footer { margin-top: 56px; color: var(--muted); font-size: 14px; border-top: 1px solid var(--line); padding-top: 16px; }
code { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 0.92em; }
.card ul { margin: 0; }

/* 按语言只显示一种：中文或英文 */
html[data-lang="zh"] [lang="en"],
html[data-lang="en"] [lang="zh-Hans"] { display: none !important; }
html[data-lang] section + section { border-top: 0; margin-top: 0; padding-top: 0; }