兼容IE7，IE8的背景漸變色

具體兼容代碼如下：

.box{

background: -webkit-gradient(linear, 0 0, 0 100%, from(#eee), to(#aaa)); /** Chrome Safari **/

background: -moz-linear-gradient(top, #eee, #aaa); /** FireFox **/

background: -o-linear-gradient(top, #eee, #aaa);/** Opear **/ 

background: -ms-linear-gradient(#eeeeee 0%,#aaaaaa 100%);/** IE9 IE10 **/

filter:progid:DXImageTransform.Microsoft.gradient(startColorstr='#eeeeee',endColorstr='#aaaaaa',grandientType=1); /** IE7 **/ 

    -ms-filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#eeeeee',endColorstr='#aaaaaa',grandientType=1); /** IE8 **/

}