Document
body,html{width: 100%;overflow: hidden;height: 100%;} #wrapper { position: relative; height:auto; overflow: hidden; width:640px; margin:0 auto;display: none; } section { position: relative; width:640px; height: 1008px; overflow: hidden;z-index: 1; } section .bg { position: absolute; left:0; top: 0; width: 100%; height: 1008px; background-size:auto 1008px;z-index: 1;}