/* Parie commune à toutes les tailles d'écran */
*{
    margin:0;
    padding: 0;
    height: 100%;
    width: 100%;
    
    font-family: Arial;    
}

img {
    width: 100%;
    height: auto;
}



@media screen and (max-width:480px) {
    body {
        background-color: green;
        color: white;
    }
}

/* pour les tablette */
@media screen and (min-width:481px) and (max-width:768px) {  /* directive CSS */
    body {
        background-color:white;
        color: black;
    }
}
@media screen and (min-width:1200px) {
    body {
        background-color: blue;
        color: white;
    }
}