owncast/web/components/video/Player.module.scss

.player {
  height: auto !important;
  width: 100%;
  video {
    position: static !important;
  }
}

.poster {
  width: 100%;
  height: 100%;
}

@media (max-width: 768px) {
  .player {
    height: 30vh !important;
  }
}