html:before,html:after,body:before,body:after{content:"";background:#fff;position:fixed;display:block;z-index:5}html:before{height:0;left:0;right:0;top:0}html:after{width:0;top:0;right:0;bottom:0}body:before{height:0;right:0;bottom:0;left:0}body:after{width:0;top:0;bottom:0;left:0}