html { scroll-behavior: smooth; }
section { scroll-margin-top: 5rem; }
.fade-in { opacity: 1; }
.js .fade-in { opacity: 0; }
@media (prefers-reduced-motion: no-preference) {
  .js .fade-in { transform: translateY(16px); transition: opacity .6s ease, transform .6s ease; }
  .fade-in.visible { transform: none; }
}
.fade-in.visible { opacity: 1; }