<style>

.mask {

  position: fixed;

  top: 0;

  left: 0;

  width: 100%;

  height: 200px;

  background: rgba(0, 0, 0, 0.5);

  display: flex;

  justify-content: center;

  align-items: center;

  z-index: 9999;

}

</style>