/* Header (builds on base.css) */
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  background: color-mix(in oklab, var(--color-bg-card) 75%, transparent);
  border-bottom: 1px solid var(--color-gray-200);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}
.header-inner {
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
/* Brand */
.brand-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--color-text-primary);
}
.brand-link:hover .brand-name { color: var(--color-primary-dark); }
.brand-mark {
  width: 12px;
  height: 12px;
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-glow);
  background: linear-gradient(135deg, var(--color-sunset-orange), var(--color-sunset-peach));
}
.brand-name {
  font-family: var(--font-display);
  font-weight: var(--font-weight-bold);
  letter-spacing: var(--letter-spacing-tight);
}
/* Navigation */
.site-nav { display: block; }
.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}
.nav-link {
  color: var(--color-text-primary);
  font-weight: var(--font-weight-medium);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-base);
}
.nav-link:hover {
  color: var(--color-primary-dark);
  background-color: var(--color-gray-100);
}
.nav-link:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}
/* Toggle (hidden on desktop) */
.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  color: var(--color-text-primary);
  border-radius: var(--radius-lg);
}
.nav-toggle:hover { background-color: var(--color-gray-100); }
.nav-toggle:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 2px; }
.nav-toggle-icon { font-size: 1.25rem; }

/* Overlay for mobile */
.nav-overlay {
  display: none;
}

/* Mobile styles */
@media (max-width: 768px) {
  .nav-toggle { display: inline-flex; }
  .site-nav {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--color-bg-card);
    box-shadow: var(--shadow-md);
    max-height: calc(100vh - var(--header-height));
    overflow-y: auto;
    transform-origin: top center;
    transition: transform var(--transition-slow) var(--easing-in-out),
                opacity var(--transition-base) var(--easing-in-out),
                visibility var(--transition-base) var(--easing-in-out);
  }
  .nav-list {
    flex-direction: column;
    align-items: stretch;
    padding: var(--space-4);
    gap: var(--space-2);
  }
  .nav-link { padding: var(--space-3) var(--space-4); }
  /* Progressive enhancement: visible by default without JS */
  html.has-js .site-nav { opacity: 0; visibility: hidden; transform: translateY(-8px); }
  html.has-js .site-nav.is-open { opacity: 1; visibility: visible; transform: translateY(0); }
  .nav-overlay {
    position: fixed;
    inset: 0;
    top: var(--header-height);
    background: var(--color-bg-overlay);
    transition: opacity var(--transition-base) var(--easing-in-out),
                visibility var(--transition-base) var(--easing-in-out);
  }
  html.has-js .nav-overlay { display: block; opacity: 0; visibility: hidden; }
  html.has-js .nav-overlay.is-active { opacity: 1; visibility: visible; }
}

/* Reduce motion */
@media (prefers-reduced-motion: reduce) {
  .site-nav { transition: none; }
  .nav-overlay { transition: none; }
}