/* Header styles (builds on base.css) */
.site-header { position: sticky; top: 0; z-index: 50; background: color-mix(in oklab, var(--color-bg-elevated) 92%, black); box-shadow: var(--shadow-1); border-bottom: 1px solid rgba(255,255,255,0.06); }
.header__inner { display: flex; align-items: center; justify-content: space-between; padding-block: var(--space-3); }

/* Skip link */
.skip-link { position: absolute; left: -9999px; top: auto; width: 1px; height: 1px; overflow: hidden; }
.skip-link:focus { left: var(--space-4); top: var(--space-4); width: auto; height: auto; padding: var(--space-2) var(--space-3); background: var(--color-primary); color: #0b1112; border-radius: var(--radius-s); box-shadow: var(--shadow-2); z-index: 100; }

/* Brand */
.brand { display: inline-flex; align-items: center; gap: var(--space-3); color: var(--color-heading); text-decoration: none; }
.brand:hover { text-decoration: none; color: var(--color-primary); }
.brand__mark { border-radius: var(--radius-xs); box-shadow: 0 0 0 1px rgba(255,255,255,0.04), var(--shadow-1); }
.brand__name { font-family: var(--font-display); font-size: var(--fs-600); letter-spacing: 0.02em; }

/* Navigation */
.nav { display: block; }
.nav__list { display: flex; align-items: center; gap: clamp(12px, 2vw, 28px); margin: 0; padding: 0; }
.nav__link { color: var(--color-text); font-weight: 600; text-decoration: none; padding: var(--space-2) var(--space-2); border-radius: var(--radius-s); }
.nav__link:hover { color: var(--color-primary); text-decoration: underline; }
.nav__link:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 2px; }

/* Menu toggle */
.menu-toggle { display: none; align-items: center; justify-content: center; width: 44px; height: 40px; border-radius: var(--radius-m); border: 1px solid var(--gray-600); background: var(--gray-800); color: var(--color-text); box-shadow: var(--shadow-1); }
.menu-toggle:hover { border-color: color-mix(in oklab, var(--color-primary) 40%, var(--gray-600)); }
.menu-toggle:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 2px; }
.menu-toggle__bars { position: relative; width: 20px; height: 14px; display: inline-block; }
.menu-toggle__bars > span { position: absolute; left: 0; right: 0; height: 2px; background: var(--color-text); border-radius: 2px; transition: transform var(--duration-base) var(--ease-out), opacity var(--duration-base) var(--ease-out); }
.menu-toggle__bars > span:nth-child(1) { top: 0; }
.menu-toggle__bars > span:nth-child(2) { top: 6px; }
.menu-toggle__bars > span:nth-child(3) { bottom: 0; }

/* Mobile behavior only when JS is available */
@media (max-width: 960px) {
  html.has-js .menu-toggle { display: inline-flex; }
  html.has-js .nav { position: fixed; inset: 64px 0 0 0; background: linear-gradient(180deg, color-mix(in oklab, var(--color-bg-elevated) 95%, black), var(--color-surface)); border-top: 1px solid rgba(255,255,255,0.06); transform: translateY(-100%); visibility: hidden; opacity: 0; transition: transform var(--duration-slow) var(--ease-out), opacity var(--duration-base) var(--ease-out); }
  html.has-js .nav.is-open { transform: translateY(0); visibility: visible; opacity: 1; }
  html.has-js .nav__list { flex-direction: column; align-items: flex-start; padding: var(--space-6); gap: var(--space-4); }
  html.has-js .nav__link { width: 100%; padding: var(--space-3) var(--space-2); font-size: var(--fs-500); }
  .nav-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.55); opacity: 0; visibility: hidden; transition: opacity var(--duration-base) var(--ease-out); }
  .nav-overlay.is-active { opacity: 1; visibility: visible; }
}

/* Toggle animation to X */
html.has-js .nav.is-open + .nav-overlay + .noop {}
html.has-js .menu-toggle[aria-expanded="true"] .menu-toggle__bars > span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
html.has-js .menu-toggle[aria-expanded="true"] .menu-toggle__bars > span:nth-child(2) { opacity: 0; }
html.has-js .menu-toggle[aria-expanded="true"] .menu-toggle__bars > span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }