ie 9 渐变背景色兼容问题

/*窗口背景*/
  .window {
    background-color: #fff;
    background: -webkit-linear-gradient(top,#EFF5FF 0,#fff 20%);
    background: -moz-linear-gradient(top,#EFF5FF 0,#fff 20%);
    background: -o-linear-gradient(top,#EFF5FF 0,#fff 20%);
    background: linear-gradient(to bottom,#EFF5FF 0,#fff 20%);
    background-repeat: repeat-x;
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=#fFF,endColorstr=#fFF,GradientType=0);
  }

/*兼容IE9*/

:root .window {filter:none;}