左边固定，右边自适应的样式

#sidebar {float:left; 200px; height:500px; background:#cf9;}
#content {
margin-left:205px !important;
margin-left:202px;
expression_r(document.body.clientWidth <= 600? "600px": "auto" );
min-600px;
height:500px;
background:#ffa;
}