/* Three primary tabs remain usable down to 320px. */
@media (max-width: 640px) {
  .site-header { gap: 12px; padding: 0 16px; }
  .site-brand { font-size: 21px; }
  .site-nav { gap: 14px; }
  .site-nav a { font-size: 12px; }
  .site-theme-toggle { padding: 8px 10px; font-size: 12px; }
}
@media (max-width: 374px) {
  .site-header { gap: 9px; padding: 0 12px; }
  .site-brand { font-size: 19px; }
  .site-nav { gap: 10px; }
  .site-nav a { font-size: 11px; }
  .site-theme-toggle { padding: 8px; font-size: 11px; }
}