.wrapper{width:600px;height:600px;background:yellow;}
header{width:100%;height:100px;background:pink;}
#content{width:100%;height:400px;}
footer{width:100%;height:100px;background:grey;}
.clear{clear:both;}

/** layouts 1 **/
#layout1 #left{width:50%;height:400px;background:green;float:left;}
#layout1 #right{width:50%;height:400px;background:red;float:left;}


/** layouts 2 **/



/** layouts 3 **/