.seo-shell {
  max-width: 1180px;
  margin: 0 auto;
  padding: 24px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: #172033;
}

.seo-shell a { color: #1d4ed8; text-decoration: none; }
.seo-shell a:hover { text-decoration: underline; }
.seo-header { display: flex; align-items: baseline; gap: 12px; padding-bottom: 18px; border-bottom: 1px solid #e5e7eb; }
.seo-header a { font-size: 20px; font-weight: 700; color: #111827; }
.seo-header span, .seo-intro, .seo-breadcrumb, .seo-sites span { color: #64748b; }
.seo-shell main { padding: 24px 0; }
.seo-shell h1 { margin: 0 0 8px; font-size: 28px; }
.seo-shell h2 { margin: 24px 0 10px; font-size: 20px; }
.seo-shell h3 { margin: 14px 0 6px; font-size: 16px; }
.seo-shell ul { margin: 0; padding-left: 20px; }
.seo-shell li { margin: 5px 0; line-height: 1.55; }
.seo-groups > section, .seo-sites li { padding: 14px 16px; border: 1px solid #e5e7eb; border-radius: 10px; }
.seo-groups > section { margin-top: 16px; }
.seo-sites { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 10px; padding: 0; list-style: none; }
.seo-sites span { display: block; margin-top: 3px; font-size: 13px; }
.seo-category-links { display: flex; flex-wrap: wrap; gap: 8px 18px; }
.seo-shell footer { margin-top: 30px; padding-top: 16px; border-top: 1px solid #e5e7eb; color: #64748b; font-size: 13px; }
.seo-not-found { text-align: center; padding-top: 15vh; }

html.dark .seo-shell { color: #e5e7eb; }
html.dark .seo-shell a { color: #60a5fa; }
html.dark .seo-header, html.dark .seo-shell footer { border-color: #273244; }
html.dark .seo-header a { color: #f8fafc; }
html.dark .seo-groups > section, html.dark .seo-sites li { border-color: #273244; background: #111827; }

@media (max-width: 640px) {
  .seo-shell { padding: 16px; }
  .seo-shell h1 { font-size: 24px; }
  .seo-header { align-items: flex-start; flex-direction: column; gap: 4px; }
}