div.di{
	float:left;
	position:relative;
	width:400px;
	height:300px;
	margin:10px;
}
div.di img{
	position:absolute;
	width:100%;
	height:100%;
	filter:alpha(opacity=0); /*IE滤镜，透明度*/
	-moz-opacity:0; /*Firefox私有，透明度*/
	opacity:0;/*其他，透明度*/
}