body {
    margin: 16px
}

.image-grid {
    --gap: 12px;
    --num-cols: 4;
    --row-height: 240px;

    box-sizing: border-box;
    padding: var(--gap);
    
    display: grid;
    grid-template-columns: repeat(var(--num-cols), 1fr);
    grid-auto-rows: var(--row-height);
    gap: var(--gap)
}

.image-grid > img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
}