@media only screen and ( min-width: 950px ) {
    /* breites Browserfenster */
    body { background-color: lightpink;}
}
@media only screen and ( max-width: 440px ) {
    /* mobile Geräte */
    body { background-color: green;}
}
@media only screen and ( min-width: 440px ) and ( max-width: 950px ) {
    /* Tablets und mittlere Bildschirme */
    body { background-color: red;}
}