/* show the 50% image first and then when the screen gets small, show the 25% variant. */
.image-scaling img.img-original {
    display: none;
}

.image-scaling img.img-25 {
    display: none;
}

.image-scaling img.img-50 {
    display: block;
}

@media screen and (max-width: 480px) {
    .image-scaling img.img-25 {
        display: block;
    }

    .image-scaling img.img-50 {
        display: none;
    }
}