.leftad1{float:right; 
position:fixed !important; top:50px; 
position:absolute; z-index:300; top:expression(offsetParent.scrollTop+200);left:20px;} 
.rightad1{float:right; 
position:fixed !important; top:50px; 
position:absolute; z-index:300; top:expression(offsetParent.scrollTop+200);right:20px;}