#sidebar {float:left; width:200px; height:500px; background:#cf9;}
#content {
margin-left:205px !important;
margin-left:202px;
width:expression_r(document.body.clientWidth <= 600? "600px": "auto" );
min-width:600px;
height:500px;
background:#ffa;
}
原文：http://www.cnblogs.com/smght/p/4380207.html