body：
.landing-bg { height: 100%; background: url(背景链接地址) no-repeat; -webkit-background-size: cover; -moz-background-size: cover; -ms-background-size: cover; -o-background-size: cover; background-size: cover; overflow: hidden; }
Div上定义背景图片
.s-skin-container {
position: absolute;
top: 0;
left: 0;
height: 100%;
width: 100%;
z-index: -10;
background-position: center 0;
background-repeat: no-repeat;
background-attachment: fixed;
background-size: cover;
-webkit-background-size: cover;
-o-background-size: cover;
zoom: 1;
}
原文：http://www.cnblogs.com/xinlinux/p/3983666.html