/* Header (scoped) */
:root { --header-height: 72px; }
.site-header {
  position: sticky;
  top: 0;
  z-index: var(--z-index-sticky);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-gray-200);
  backdrop-filter: saturate(180%) blur(6px);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: var(--header-height);
  gap: var(--space-4);
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  font-weight: var(--font-weight-bold);
  font-size: var(--font-size-lg);
  color: var(--color-text-primary);
}
.brand:hover { color: var(--color-primary-dark); }
.brand-mark {
  width: 28px; height: 28px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  box-shadow: var(--shadow-sm);
}
.brand-text { letter-spacing: var(--letter-spacing-tight); }

/* Navigation */
.primary-nav { position: relative; }
.nav-list {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}
.nav-list a {
  color: var(--color-text-primary);
  font-weight: var(--font-weight-medium);
}
.nav-list a:hover { color: var(--color-primary-dark); }
.nav-cta { margin-left: var(--space-2); }

/* Mobile toggle */
.nav-toggle {
  display: none;
  color: var(--color-text-primary);
  padding: var(--space-2);
  border-radius: var(--radius-md);
  border: 1px solid transparent;
}
.nav-toggle:hover { color: var(--color-primary-dark); }
.nav-toggle:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Progressive enhancement: only collapse nav on small screens when JS is enabled */
@media (max-width: 1024px) {
  .nav-toggle { display: inline-flex; }
  .nav-list { gap: var(--space-4); }
  .js .primary-nav {
    position: fixed;
    top: var(--header-height);
    left: 0; right: 0;
    background: var(--color-surface);
    border-top: 1px solid var(--color-gray-200);
    box-shadow: var(--shadow-md);
    transform: translateY(-8px);
  }
  .js .primary-nav .nav-list {
    flex-direction: column;
    align-items: stretch;
    padding: var(--space-4);
  }
  .js .primary-nav:not(.is-open) { display: none; }
  .js .primary-nav.is-open { display: block; animation: menuSlide var(--transition-slow); }
  @keyframes menuSlide { from { opacity: 0; transform: translateY(-8px);} to { opacity: 1; transform: translateY(0);} }
}

/* Backdrop for mobile menu */
.nav-backdrop {
  position: fixed; inset: 0; background: rgba(15, 23, 42, 0.45);
  z-index: calc(var(--z-index-sticky) - 1);
  opacity: 0; pointer-events: none; transition: opacity var(--transition-slow);
}
.nav-backdrop.is-active { opacity: 1; pointer-events: auto; }

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  .nav-backdrop { transition: none; }
}