#wpmg-gallery {
    columns: 4 300px;
    column-gap: 20px;
}

.wpmg-item {
    display:block;
    break-inside:avoid;
    margin-bottom:20px;
}

.wpmg-item img {
    width:100%;
    height:auto;
    display:block;
    border-radius:10px;
}