a.thumbnail {
    display: inline-block;
    width: 24%;
    height: 300px;
    font-size: 0px;
    line-height: 0px;
    margin: 0px 8px 10px 0px;
    border: 2px solid #DDD;
    overflow: hidden;
}

    a.thumbnail img {
        width: 100%;
        height: 100%;
        object-fit: cover;
    }