跨浏览器投影实现

.shadow{
		/* hack for ie */
		background: #fff;
		
		/* sane web browsers */
		-moz-box-shadow:1px 3px 12px #bbb;
		-webkit-box-shadow:1px 3px 12px #bbb;
		box-shadow:1px 3px 12px #bbb;
		
		/* gte ie8 */
		-ms-filter:"progid:DXImageTransform.Microsoft.Shadow(color=#eeeeee,direction=0,strength=6) progid:DXImageTransform.Microsoft.Shadow(color=#dddddd,direction=90,strength=10) progid:DXImageTransform.Microsoft.Shadow(color=#dddddd,direction=180,strength=10) progid:DXImageTransform.Microsoft.Shadow(color=#eeeeee,direction=270,strength=6)";
		
		/* lte ie7 */
		*filter: 
        progid:DXImageTransform.Microsoft.Shadow(color=#eeeeee,direction=0,strength=6)
        progid:DXImageTransform.Microsoft.Shadow(color=#dddddd,direction=90,strength=10)
        progid:DXImageTransform.Microsoft.Shadow(color=#dddddd,direction=180,strength=10)
        progid:DXImageTransform.Microsoft.Shadow(color=#eeeeee,direction=270,strength=6);
	}