style.css

.grid li.page-list-item a .icon {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 100%;
    height: 100%;
    margin: 0;
    max-height: 50%;
    max-width: inherit;
    transform: translate(-50%, 0%);
}

.grid li.page-list-item a .icon img
{
    margin: auto;
    object-fit: contain;
    width: inherit;
    height: inherit;
}