discourse/components/video-overlay/common/common.scss

#overlay-video {
  pointer-events: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  opacity: 0.25;
  z-index: 1001;
  width: 100vw;
  height: 100vh;
  object-fit: cover;
  max-height: 100vh;
}