*{margin:0px;padding:0px;}
body{color:pink;font-size:16px;font-family:arial;background:#eee;}
#box{margin:50px auto;width:500px;height:600px;border:2px solid black;}
header{width:100%;height:100px;background:red;}
.content{width:100%;height:400px;}
footer{width:100%;height:100px;background:green}

/** layout 1 **/
#layout #left{width:50%;height:400px;background:cyan;float:left;}
#layout #right{width:50%;height:400px;background:#fff;float:left;}

/** layout 2 **/


/** layout 3 **/