.baocuncg{
background: rgba(0,0,0,0.7);
color: #ffffff;
border-radius: 5px;
text-align: center;
line-height: 40px;
z-index:99;
300px;
height: 120px;
left:50%;/*FF IE7*/
top: 50%;/*FF IE7*/
margin-left:-150px!important;/*FF IE7 该值为本身宽的一半 */
margin-top:-60px!important;/*FF IE7 该值为本身高的一半*/
margin-top:0px;
position:fixed!important;/*FF IE7*/
position:absolute;/*IE6*/
_top: expression(eval(document.compatMode &&
document.compatMode=='CSS1Compat') ?
documentElement.scrollTop + (document.documentElement.clientHeight-this.offsetHeight)/2 :/*IE6*/
document.body.scrollTop + (document.body.clientHeight - this.clientHeight)/2);/*IE5 IE5.5*/
}