.column-portfolio_item_post_thumbs img {
    width: 100%;
    max-width: 100%;
    height: auto;
}

@media screen and (max-width: 782px) {
    .column-portfolio_item_post_thumbs {
        display: none;
    }

    .column-portfolio_item_post_thumbs:before {
        display: none !important;
    }

}