.cadre {
    top:50%;left:50%;
    position:absolute;
    width:800px;height:600px;
    margin-left:-400px;
    margin-top:-300px;
    object-fit: scale-down;
    background-image: url(fenetre.png);
    background-position:center center;
    background-repeat: no-repeat;
    background-size: cover;  
    }

    #sun {
    top:100px;left:100px;
    width:80px;height:80px;
    background-image: url(sun.png);
    background-position:center center;
    background-repeat: no-repeat;
    background-size: cover;  
    }