/* Header: invisible at the top of the page, a floating glass pill once you scroll. */
.navigation{
  background:transparent;border-color:transparent;box-shadow:none;
  -webkit-backdrop-filter:none;backdrop-filter:none;
  transform-origin:50% 0;
  transition:background-color .7s ease-in-out,border-color .7s ease-in-out,box-shadow .7s ease-in-out,transform .7s ease-in-out,-webkit-backdrop-filter .7s ease-in-out,backdrop-filter .7s ease-in-out;
}
.navigation.is-scrolled,
.navigation:has(#menu-toggle[aria-expanded="true"]){
  background:var(--nav);border-color:var(--line);box-shadow:0 7px 15px var(--shadow);
  -webkit-backdrop-filter:blur(18px);backdrop-filter:blur(18px);
  transform:scale(.98);
}
@media (prefers-reduced-motion:reduce){
  .navigation{transition:none}
}