.top-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  transform: translateY(0);
  transition: transform 200ms ease;
  will-change: transform;
  background-color: rgba(255, 255, 255, 0.85);
  background-color: hsl(var(--b1, 0 0% 100%) / 0.85);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.08);
  border-bottom: 1px solid hsl(var(--b2, 0 0% 90%) / 0.65);
}

.top-nav--hidden {
  transform: translateY(-100%);
}

.top-nav--scrolled {
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.08);
}

@media (prefers-reduced-motion: reduce) {
  .top-nav {
    transition: none;
  }
}