body {
margin-top:0px;
margin-right:0px;
margin-bottom:0px;
margin-left:0px;
background-color:#CCDAF7;
background-image:url(../images/loadbg.jpg);
background-repeat:no-repeat;
background-position:top;
background-attachment:fixed;
}
CSS样式中,background-image 背景图片居中显示并且在不同屏幕分辨率下始终居中
原文：http://www.cnblogs.com/shawn-en/p/4368560.html
