如果是个背景图的话,
定义一个div,高100%,宽100%,里面放个img
<div class='bg'>
<img src="data:images/bg.jpg" alt="">
</div> html,body{overflow: hidden;}
.bg{width: 100%;height: 100%;top:0;z-index: -1; position: absolute;}
.bg img{display: block;outline: none;border:0;height: 100%;width: 100%;}