#gal1 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-column-gap: 5px;
    grid-row-gap: 5px;
}

#gal1 img {
    border-radius: 20px;
}

@media (max-width: 768px) {
    #gal1 a:nth-child(1){
        grid-column: 1 / -1;
    }
    #gal1 a:nth-child(4), #gal1 a:nth-child(5){
        grid-area: 6;
    }
    #gal1 a:nth-child(8){
        grid-column: 1 / -1;
    }
}

@media (min-width: 768px) {
    #gal1 {
        grid-template-columns: 1fr 1fr 1fr 1fr;
        gap: 10px;
    }
    #gal1 a:nth-child(1){
        grid-column: 1 / 3;
        grid-row: 1 / 3;

    }
    #gal1 a:nth-child(8){
        grid-column: 3 / 5;
        grid-row: 3 / 5;
    }
}