#gallery{
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 20px;
}

#gallery > img{
    margin-right: auto;
    margin-left: auto;
}

@media screen and (max-width: 981px) {
    #gallery{
        grid-template-columns: 1fr 1fr;
    }
}