1.新增<video>

<video class="video-background" autoplay muted loop>
  <source src="../../assets/starry-sky.mp4" type="video/mp4" />
  Your browser does not support the video tag.
</video>

2.新增CSS样式

.video-background {
  position: fixed;
  top: 0;
  left: 0;
  min-width: 100%;
  min-height: 100%;
  width: auto;
  height: auto;
  z-index: -1;
}