CSS issues in IE8

CSS issues in IE8

Im having 2 Div's , one Div should appear beside another Div, and its
working the same way as expected in all the browsers but in IE8, the right
div is appearing below left div, the same is working fine in IE9, But the
issue is with only IE8,how to overcome this as i dont have much experience
on working with Css
.leftcontent {
background: none repeat scroll 0 0 #;
float: left;
height: 500px;
width:25%;
}
.rightcontent {
background: none repeat scroll 0 0 #;
float: left;
height: 500px;
width:80%;
}