#adultclassesDiv {
    background-image: url('/storage/app/media/adult-classes/adults.png');
    background-size: 100%;
    height: 500px;
}

@media only screen and (min-device-width: 320px) and (max-device-width: 480px) and (-webkit-min-device-pixel-ratio: 2) {
    #adultclassDiv {
           height: 160px;
    }
}