来源 | https://www.cnblogs.com/front-girl/archive/2018/03/23/8628571.html

.fullscreenvideo {    position: absolute;    top: 50%;    left: 50%;    min-width: 100%;    min-height: 100%;    width: auto;    height: auto;    z-index: -100;    -webkit-transform: translateX(-50%) translateY(-50%);    transform: translateX(-50%) translateY(-50%);    -webkit-transition: 1s opacity;    transition: 1s opacity;}
.videocontainer{    position: fixed;    width: 100%;    height: 100%;    overflow: hidden;    z-index: -100; }
.videocontainer:before{    content: "";    position: absolute;    width: 100%;    height: 100%;    display: block;    z-index: -1;    top: 0;    left: 0;    background: rgba(25,29,34,.65);}