.app-shell > header {
  background: #fff;
  position: sticky;
  top: 0;
  transform: translateY(0);
  transition: transform 220ms ease, box-shadow 220ms ease;
  will-change: transform;
  z-index: 1000;
}

.app-shell > header:has(+ main) {
  box-shadow: 0 3px 14px rgba(15, 23, 42, 0.08);
}

.scroll-header-hidden .app-shell > header {
  box-shadow: none;
  pointer-events: none;
  transform: translateY(-100%);
}

@media (prefers-reduced-motion: reduce) {
  .app-shell > header {
    transition: none;
  }
}