.sgm-gallery {
    display: flex;
    flex-wrap: wrap;
    gap: 5px;
}

.sgm-gallery a {
    width: 150px;      /* fixed width */
    height: 150px;     /* fixed height */
    display: block;
    overflow: hidden;  /* crop any overflow */
}

.sgm-gallery a img {
    width: 100%;
    height: 100%;
    object-fit: cover;  /* scale & crop to fill */
    display: block;
}