img.mob-img {
    width: 250px;
    height: 400px;
}
@media screen and (max-width: 992px) {
    img.mob-img {
        width: 200px;
        height: 400px;
    }
}
@media screen and (max-width: 600px) {
    img.mob-img {
        width: 100px;
        height: auto;
    }
}