.un {
    background-color: yellow;   
    
    height: 400px;
    width: 400px;

    margin: 200px auto;
}

.deux {
    background-color: rgb(189, 186, 1);

    height: 300px;
    width: 300px;

    margin-left: 45px;
    margin-top: 45px;
}

.trois {
    background-color: rgb(100, 102, 1);

    height: 200px;
    width: 200px;

    margin-left: 50px;
    margin-top: 70px;

    
}

.quatre {
    background-color: rgb(43, 42, 0);

    height: 100px;
    width: 100px;

    margin-top: 70px;
    margin-left: 50px;
    

}