Hi All, Im having this issue with margin-top eating away my time. i have the sample layout test page as below

#container {
margin-left: 0px;
width: 1000px;
height:1200px;
}
#rightCol {
position: absolute;top: 30px; margin-left: 125px; margin-right:auto;width:841px; height:1100px; border-radius:15px;behavior:url(border-radius.htc);background:#CCC;z-index:1; 
}
#outercontent {background:green;position:absolute;padding:10px;font-size:12px; align:center;width:830px;
margin-top:5px; margin-bottom:1px;margin-left:3px; margin-right:3px;vertical-align:middle;
overflow:auto;overflow:hidden;line-height: 150%;z-index:1;
}
.content5{width:290px;padding:10px;padding-left:15px;padding-right:8px;font-size:12px;float:left; 
vertical-align:top; background:#FFF; margin:0px;margin-top:5px;}
.content6{width:470px;padding-top:10px;padding-left:15px;padding-right:8px;margin-top:5px;margin-bottom:5px;
font-size:12px;float:right; margin-left:9px;vertical-align:top; background:#FFF;margin-right:0px;}
.content7{width:425px;height:180px;padding-top:10px;padding-left:15px;padding-right:8px;font-size:12px;float:left; 
vertical-align:top; background:#FFF; margin-top:10px;margin-right:5px;margin-bottom:5px;margin-left:0px;clear:left;}
.content8{width:335px;height:280px;padding:10px;padding-left:15px;padding-right:8px;margin:auto;
font-size:12px;float:right;vertical-align:top; background:#FFF;clear:right;}
.content9{width:310px;height:212px;padding:10px;padding-left:15px;padding-right:8px;font-size:12px;float:left; 
vertical-align:top; background:#FFF; margin:0px;margin-top:5px;}
.content10{width:450px;padding:10px;padding-left:15px;padding-right:8px;margin-top:5px;
font-size:12px;float:right; margin-left:9px;vertical-align:top; background:#FFF;margin-right:0px;}

now the content8 div should come below the content 6. i added margin-top:5px to give some space between the two divs. this works differently in the browsers. it works fine in IE but firefox and chrome wants a value of -53px; please help.im running out of time and this issue is boggling me.