:root {
  color-scheme: light;
  --bg: #f6f8fb;
  --card: #ffffff;
  --text: #172033;
  --muted: #667085;
  --border: #e4e7ec;
  --accent: #1677ff;
  --code-bg: #0f172a;
  --code-text: #e2e8f0;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
}
.header {
  background: linear-gradient(135deg, #111827, #1f2937);
  color: #fff;
  padding: 48px 20px;
}
.header-inner { max-width: 980px; margin: 0 auto; }
.header h1 { margin: 0 0 12px; font-size: 34px; line-height: 1.25; }
.header p { color: #d1d5db; margin: 0; font-size: 16px; }
.container {
  max-width: 980px;
  margin: -28px auto 60px;
  padding: 0 20px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 18px;
  padding: 30px;
  box-shadow: 0 12px 40px rgba(15, 23, 42, 0.08);
}
h1, h2, h3, h4 { line-height: 1.35; margin-top: 1.6em; margin-bottom: .7em; }
h1 { font-size: 30px; }
h2 { font-size: 24px; padding-top: 10px; border-top: 1px solid var(--border); }
h3 { font-size: 20px; }
p { margin: .8em 0; }
a { color: var(--accent); }
code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  background: #eef2ff;
  color: #1e3a8a;
  padding: 2px 6px;
  border-radius: 6px;
  font-size: .92em;
}
.code-block {
  margin: 16px 0;
  border-radius: 14px;
  overflow: hidden;
  background: var(--code-bg);
}
.code-lang {
  color: #93c5fd;
  font-size: 12px;
  padding: 8px 14px 0;
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}
pre {
  margin: 0;
  padding: 14px;
  overflow-x: auto;
}
pre code {
  background: transparent;
  color: var(--code-text);
  padding: 0;
  border-radius: 0;
}
table {
  border-collapse: collapse;
  width: 100%;
  margin: 18px 0;
  overflow: hidden;
  border-radius: 12px;
  border: 1px solid var(--border);
}
th, td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}
th { background: #f2f4f7; font-weight: 700; }
tr:last-child td { border-bottom: none; }
blockquote {
  border-left: 4px solid var(--accent);
  background: #eff6ff;
  margin: 16px 0;
  padding: 10px 14px;
  border-radius: 8px;
}
ul, ol { padding-left: 1.4em; }
.footer { color: var(--muted); text-align: center; margin-top: 24px; font-size: 13px; }
@media (max-width: 640px) {
  .header h1 { font-size: 26px; }
  .card { padding: 20px; }
}