/* Header (builds on base.css) */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--color-surface);
  border-bottom: 1px solid var(--gray-200);
  box-shadow: var(--shadow-xs);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  gap: var(--space-6);
}
.brand-link { display: inline-flex; align-items: center; gap: var(--space-3); font-weight: 900; letter-spacing: 0.01em; }
.brand-logo { width: 36px; height: 36px; border-radius: 10px; box-shadow: var(--shadow-xs); }
.brand-name { color: var(--color-text); font-size: clamp(1.125rem, 2.4vw, 1.375rem); }

/* Skip to content */
.skip-link {
  position: absolute;
  left: 8px; top: -100px;
  background: var(--color-focus);
  color: #ffffff;
  padding: 10px 14px;
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-sm);
  transition: top var(--duration-base) var(--ease-standard);
  z-index: 1001;
}
.skip-link:focus { top: 8px; outline: var(--ring-width) solid #ffffff; }

/* Navigation */
.primary-nav { display: block; }
.nav-list { display: flex; align-items: center; gap: clamp(8px, 2vw, 20px); list-style: none; margin: 0; padding: 0; }
.nav-item a { display: inline-block; padding: 10px 12px; border-radius: var(--radius-pill); font-weight: 700; color: var(--color-text); }
.nav-item a:hover, .nav-item a:focus-visible { background: var(--color-primary-100); text-decoration: none; outline: var(--ring-width) solid transparent; }
.nav-item a:focus-visible { box-shadow: 0 0 0 3px rgba(79,163,227,0.35); }

/* Menu toggle (mobile) */
.menu-toggle { display: none; align-items: center; gap: var(--space-2); border: 1px solid var(--gray-300); background: var(--color-surface); color: var(--color-text); padding: 8px 12px; border-radius: var(--radius-pill); }
.menu-toggle:hover { background: var(--gray-100); }
.menu-toggle:focus-visible { outline: var(--ring-width) solid var(--color-focus); }
.menu-icon { font-size: 1.1rem; }
.menu-label { font-weight: 800; }

/* Responsive behavior */
@media (max-width: 960px) {
  .menu-toggle { display: inline-flex; }
  /* Progressive enhancement: only hide nav on small screens when JS is enabled */
  .js-enabled .primary-nav { display: none; }
  .js-enabled .primary-nav.is-open { display: block; }

  .primary-nav {
    position: fixed;
    left: 0; right: 0; top: 64px;
    background: var(--color-surface);
    border-bottom: 1px solid var(--gray-200);
    box-shadow: var(--shadow-sm);
  }
  .primary-nav .nav-list { flex-direction: column; align-items: stretch; gap: 0; padding: var(--space-3) var(--container-padding); }
  .primary-nav .nav-item a { padding: 14px; border-radius: var(--radius-md); }
}

/* Utility to lock scroll when menu open */
body.no-scroll { overflow: hidden; }