:root {
  --bg: #f7f8fb;
  --card: #fff;
  --text: #1f2430;
  --muted: #667085;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --border: #e5e7eb;
  --radius: 12px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.75;
}

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

.container { max-width: 880px; margin: 0 auto; padding: 0 20px; }

header.site {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 10;
}
header.site .container { display: flex; align-items: center; justify-content: space-between; height: 60px; }
header.site .logo { font-weight: 700; font-size: 18px; color: var(--text); }
header.site nav a { margin-left: 18px; color: var(--muted); font-size: 15px; }

.hero { padding: 56px 0 32px; text-align: center; }
.hero h1 { font-size: 32px; margin: 0 0 12px; line-height: 1.3; }
.hero p { color: var(--muted); margin: 0 auto 24px; max-width: 640px; }

.btn {
  display: inline-block;
  background: var(--primary);
  color: #fff;
  padding: 12px 28px;
  border-radius: 999px;
  font-weight: 600;
}
.btn:hover { background: var(--primary-dark); text-decoration: none; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
}

.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; }
.grid .card { margin: 0; }
.grid .card h3 { margin-top: 0; }

article h1 { font-size: 28px; line-height: 1.35; margin-bottom: 8px; }
article h2 { margin-top: 36px; padding-bottom: 6px; border-bottom: 1px solid var(--border); }
article .meta { color: var(--muted); font-size: 14px; margin-bottom: 24px; }
article img { max-width: 100%; border-radius: 8px; }

table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 15px; }
th, td { border: 1px solid var(--border); padding: 10px 12px; text-align: left; }
th { background: #f1f5f9; }

.cta {
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: #fff;
  border-radius: var(--radius);
  padding: 28px;
  text-align: center;
  margin: 32px 0;
}
.cta p { margin: 0 0 16px; }
.cta .btn { background: #fff; color: var(--primary); }

.note { background: #fff7ed; border-left: 4px solid #f97316; padding: 12px 16px; border-radius: 6px; font-size: 15px; }

details { background: var(--card); border: 1px solid var(--border); border-radius: 8px; padding: 14px 18px; margin-bottom: 10px; }
summary { cursor: pointer; font-weight: 600; }

.breadcrumb { font-size: 14px; color: var(--muted); margin: 20px 0 0; }

footer.site { color: var(--muted); font-size: 14px; text-align: center; padding: 40px 0; border-top: 1px solid var(--border); margin-top: 48px; }

@media (max-width: 600px) {
  .hero h1 { font-size: 26px; }
  header.site nav a { margin-left: 12px; font-size: 14px; }
}