.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  background: var(--color-nav);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--color-border);
  transition: box-shadow var(--transition), background var(--transition);
}

.site-header.scrolled {
  box-shadow: var(--shadow-sm);
}

.nav-shell {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: var(--space-6);
  width: 100%;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.5rem;
  text-transform: uppercase;
  letter-spacing: 0.02em;
  color: var(--color-primary);
  white-space: nowrap;
  padding-left: var(--space-2);
}

.brand-logo {
  height: 52px;
  width: auto;
  flex: 0 0 auto;
  padding-left: var(--space-3);
}

.desktop-nav {
  display: none;
  justify-content: center;
  gap: clamp(1rem, 2vw, 2rem);
}

.desktop-nav a,
.mobile-menu a {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  transition: color var(--transition);
}

.desktop-nav a:hover,
.mobile-menu a:hover {
  color: var(--color-primary);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.icon-btn {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid var(--color-border);
  display: inline-grid;
  place-items: center;
  background: var(--color-surface);
  box-shadow: var(--shadow-sm);
}

.icon-btn svg {
  width: 20px;
  height: 20px;
}

.menu-toggle {
  display: inline-grid;
}

.mobile-menu {
  position: fixed;
  inset: 0;
  background: color-mix(in srgb, var(--color-bg) 96%, transparent);
  backdrop-filter: blur(10px);
  z-index: 999;
  display: grid;
  align-content: center;
  justify-items: center;
  gap: var(--space-6);
  transform: translateY(-100%);
  opacity: 0;
  pointer-events: none;
  transition: transform 300ms ease, opacity 300ms ease;
}

.mobile-menu.open {
  transform: translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.mobile-menu a {
  font-family: var(--font-display);
  text-transform: uppercase;
  font-size: var(--text-xl);
  color: var(--color-primary);
}

@media (min-width: 768px) {
  .menu-toggle { display: none; }
  .desktop-nav { display: flex; }
}

@media (max-width: 767px) {
  .nav-actions .btn-primary {
    display: none;
  }
}