#caja {
    background-color: grey;
    height: 300px;
    width: 300px;
    float: left;
    padding: 5px;
    margin: 5px;
    border: 5px;
}
#caja1 {
    background-color: lightseagreen;
    height: 400px;
    width: 50%;
    float: left;
    padding: 5px;
    margin: 5px;
    border: 5px;
    clear: both;

}