.hero { isolation: isolate; }
.hero__video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  pointer-events: none;
  opacity: 0;
  transition: opacity .5s ease;
}
.hero__video.is-playing { opacity: 1; }
@media (prefers-reduced-motion: reduce) {
  .hero__video { display: none; }
}