.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  background: rgb(8 11 16 / 92%);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
}

@media (max-width: 620px) {
  .site-header .brand-mark { width: 42px; height: 42px; flex-basis: 42px; }
}