/* 全站统一导航头（浅色，与首页 .site-header 一致） */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(16px);
  background: rgba(255, 255, 255, 0.86);
  border-bottom: 1px solid rgba(37, 99, 235, 0.08);
  box-shadow: 0 10px 30px rgba(15, 23, 42, 0.04);
}
/* header 始终全宽，避免被页面内容宽度(.container 覆盖)压窄 */
.site-header .container { max-width: 1200px; }
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}
.nav-shell {
  min-height: 82px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  position: relative;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  letter-spacing: -0.01em;
  position: absolute;
  left: 0;
  text-decoration: none;
  color: #0f172a;
}
.brand-logo {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  object-fit: contain;
  box-shadow: 0 14px 24px rgba(37, 99, 235, 0.2);
}
.brand-text { font-size: 1.02rem; }
.site-nav {
  display: flex;
  align-items: center;
  gap: 6px;
  justify-content: center;
}
.site-nav a {
  padding: 10px 16px;
  border-radius: 999px;
  color: #64748b;
  font-weight: 600;
  transition: background 0.2s ease, color 0.2s ease;
  text-decoration: none;
}
.site-nav a:hover,
.site-nav a.is-active { color: #2563eb; background: #eff6ff; }
.menu-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 0;
  border-radius: 12px;
  background: #f1f5f9;
  cursor: pointer;
}
.menu-toggle span {
  display: block;
  width: 18px;
  height: 2px;
  margin: 4px auto;
  border-radius: 999px;
  background: #334155;
}
@media (max-width: 760px) {
  .menu-toggle { display: inline-block; position: absolute; right: 20px; }
  .brand { position: static; }
  .nav-shell { justify-content: space-between; }
  .site-nav {
    position: absolute;
    top: calc(100% + 12px);
    left: 16px;
    right: 16px;
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: 12px;
    border-radius: 20px;
    background: rgba(255, 255, 255, 0.98);
    border: 1px solid #e2e8f0;
    box-shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  }
  .site-nav.is-open { display: flex; }
}