CSS layout techniques : 3 columns, all fluid

mainleft

#mainleft {
width:33%;
float:left;
background:#fff;
padding-bottom:10px;
    }

#maincenter {
width:34%;
float:left;
background:#fff;
padding-bottom:10px;
    }

#mainright {
width:33%;
float:left;
background:#fff;
padding-bottom:10px;
    }