.row {
    display: inline-block;
}
.row > img {
    width: 50%;
    float: left;
    padding: 4px 4px;
    display: block;
}

.last-img {
    margin-bottom: 100px;
}

.workspace {
    text-align: center;
}

/*styling for tablet and desktop*/
@media (min-width: 480px) {
    .row > img {
        width: 33.33333%;
        float: left;
        padding: 4px 4px;
    }
}