/* custom.css — per-site design layer.
 *
 * Ships EMPTY. This is where a site gets a bespoke look WITHOUT forking the
 * template: it loads after site.css and theme.css, so anything here wins.
 * `sites update-template` PRESERVES this file (it's treated like config.json),
 * so template updates never clobber a site's custom design.
 *
 * Two sites built on this same template can look completely different — one
 * clean and light, another dark and technical — by living here. Use CSS
 * variables from theme.css (--color-primary, etc.) plus plain overrides of
 * the component classes in site.css (.hero, .card, .btn-primary, header,
 * footer, section bands…).
 */