/* Header (builds on base.css) */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: color-mix(in oklab, var(--color-surface) 92%, transparent);
  backdrop-filter: saturate(1.2) blur(8px);
  border-bottom: 1px solid color-mix(in oklab, var(--gray-200) 70%, transparent);
}
.header-inner { display: flex; align-items: center; justify-content: space-between; padding-block: var(--space-3); }

/* Skip link */
.skip-link {
  position: absolute; left: var(--space-4); top: -200px; z-index: 1001;
  background: var(--color-primary); color: var(--on-primary);
  padding: 8px 12px; border-radius: var(--radius-md); box-shadow: var(--shadow-md);
}
.skip-link:focus { top: var(--space-3); }

/* Brand */
.brand-wrap { display: flex; align-items: center; gap: var(--space-3); }
.brand { display: inline-flex; align-items: center; gap: var(--space-2); font-weight: 800; letter-spacing: -0.01em; color: var(--color-text); text-decoration: none; }
.brand:hover { text-decoration: none; }
.brand-mark { display: inline-flex; align-items: center; justify-content: center; width: 36px; height: 36px; border-radius: var(--radius-full); background: radial-gradient(80% 80% at 30% 30%, var(--color-primary), var(--color-accent)); color: #0a0a0a; box-shadow: var(--shadow-glow-primary); }
.brand-text { font-family: var(--font-display); font-size: clamp(1.05rem, 0.7rem + 1vw, 1.4rem); }

/* Nav */
.primary-nav { margin-left: auto; }
.nav-list { display: flex; align-items: center; gap: clamp(12px, 1.6vw, 24px); }
.nav-link { color: var(--color-text); font-weight: 600; padding: 10px 8px; border-radius: var(--radius-sm); }
.nav-link:hover { text-decoration: none; background: var(--gray-100); }
.nav-link:focus-visible { outline: 3px solid var(--focus-ring); outline-offset: 2px; }

.nav-cta .btn { padding-inline: 16px; }

/* Menu toggle */
.menu-toggle { display: none; align-items: center; gap: 10px; border: 1px solid var(--gray-300); background: var(--color-surface); color: var(--color-text); padding: 8px 12px; border-radius: var(--radius-md); box-shadow: var(--shadow-sm); cursor: pointer; }
.menu-toggle:hover { background: var(--gray-100); }
.menu-toggle:focus-visible { outline: 3px solid var(--focus-ring); outline-offset: 2px; }
.menu-toggle .burger { width: 22px; height: 2px; background: var(--color-text); position: relative; border-radius: 2px; }
.menu-toggle .burger::before, .menu-toggle .burger::after { content: ""; position: absolute; left: 0; width: 22px; height: 2px; background: var(--color-text); border-radius: 2px; transition: transform var(--duration-normal) var(--ease-spring), opacity var(--duration-normal) linear; }
.menu-toggle .burger::before { top: -6px; }
.menu-toggle .burger::after { top: 6px; }

/* Mobile / small screens */
@media (max-width: 960px) {
  .menu-toggle { display: inline-flex; }
  .primary-nav { position: fixed; left: 0; right: 0; top: 64px; /* approximate header height */ background: linear-gradient(180deg, color-mix(in oklab, var(--color-surface) 98%, transparent), color-mix(in oklab, var(--gray-100) 80%, transparent)); border-bottom: 1px solid var(--gray-200); box-shadow: var(--shadow-lg); padding: var(--space-4) var(--space-4) var(--space-6); display: block; }
  /* Progressive enhancement: hidden only when JS sets data attribute */
  .site-header[data-menu-collapsed="true"] .primary-nav { display: none; }
  .site-header[data-menu-open="true"] .primary-nav { display: block; }

  .nav-list { flex-direction: column; align-items: stretch; gap: var(--space-2); }
  .nav-link { padding: 12px; background: var(--color-surface); border: 1px solid var(--gray-200); }
  .nav-cta .btn { width: 100%; }

  /* Animate burger into X when open */
  .site-header[data-menu-open="true"] .menu-toggle .burger { background: transparent; }
  .site-header[data-menu-open="true"] .menu-toggle .burger::before { transform: translateY(6px) rotate(45deg); }
  .site-header[data-menu-open="true"] .menu-toggle .burger::after { transform: translateY(-6px) rotate(-45deg); }
}