*{margin:0px;padding:0px;}
body{color:#fff;font-size:16px;font-family:arial;background:cyan;}
.box{margin:50px auto;width:700px;height:600px;border:2px solid red;}
header{width:100%;height:100px;background:blue;}
#content{width:100%;height:400px;}
footer{width:100%;height:100px;background:green;}


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

/**   layout 2   **/


/**   layout 3   **/