.box1, .box11 {
    margin-top: 20px;
    clear: both;
    width: 950px;
    border: 1px solid black;
    background: #DDDDDD;
    padding: 5px;
}

.box2, .box12 {
    margin-top: 20px;
    width: 640px;
    float: left;
    clear: left;
    padding: 5px;
}

.box3, .box13 {
    margin-top: 20px;
    width: 300px;
    float: right;
    clear: right;
    padding: 5px;
}