#head_group .head_ad { float:left; padding:10px; width:718px; height:80px; }
#head_group .head_ad img { width:auto; height:80px; }

.ad { clear:both; float:left; padding:0px; margin:0px; width:100%; height:auto; text-align:center; overflow:hidden; }

.float_ad { clear:both; position:fixed; top:140px; left:5px; width:auto; height:auto; z-index:980; }