IE8及以下对透明度的兼容

1.opacity{
2  -khtml-opacity:0.6;
3  -moz-opacity:0.6;filter:
4  alpha(opacity=60);
5  opacity:0.6;
6  filter:"alpha(opacity=60)";
7  -ms-filter: progid:DXImageTransform.Microsoft.Alpha(Opacity=50);
8  filter: progid:DXImageTransform.Microsoft.Alpha(opacity=70);/*兼容ie8及以下*/
9}