:root {
  --header-bg: rgba(0, 0, 0, 0.72);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-accent: rgba(255, 255, 255, 0.18);
  --text-primary: #f5f5f7;
  --text-secondary: #86868b;
  --badge-bg: rgba(255, 255, 255, 0.06);
  --font-main: "Plus Jakarta Sans", -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
}

html.light {
  --header-bg: rgba(245, 245, 247, 0.8);
  --border-color: rgba(0, 0, 0, 0.08);
  --border-accent: rgba(0, 0, 0, 0.16);
  --text-primary: #1d1d1f;
  --text-secondary: #86868b;
  --badge-bg: rgba(0, 0, 0, 0.05);
}

.site-header {
  position: sticky;
  top: 0;
  width: 100%;
  background: var(--header-bg);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
}

.site-header .nav-wrapper {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 58px;
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
}

.site-header .brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  text-decoration: none;
}

.site-header .brand-tag {
  font-size: 0.72rem;
  padding: 2px 8px;
  background: var(--badge-bg);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  color: var(--text-secondary);
  font-weight: 500;
  font-family: var(--font-mono);
}

.site-header nav {
  display: flex;
  align-items: center;
  gap: 24px;
}

.site-header .nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
}

.site-header .nav-link:hover,
.site-header .nav-link.here {
  color: var(--text-primary);
}

.theme-toggle {
  background: var(--badge-bg);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.theme-toggle:hover {
  border-color: var(--border-accent);
}