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);}