#keyboard {
    background-image: url(../images/keyboard_1920.jpg);
    height: 840px;
}

@media screen and (max-width: 1366px) {
    #keyboard {
        background-image: url(../images/keyboard_1366.jpg);
        height: 600px;
    }
}

@media screen and (max-width: 960px) {
    #keyboard {
        background-image: url(../images/keyboard_960.jpg);
        height: 500px;
    }
}

@media screen and (max-width: 640px) {
    #keyboard {
        background-image: url(../images/keyboard_640.jpg);
        height: 439px;
        background-position: center -50px;
    }
}