.banner {
    display: grid;
    gap: 1rem;
}

.banner img:nth-child(1) {
    grid-column: 1/3;
}

.banner img:nth-child(4) {
    grid-column: 2/3;
    grid-row: 2/4;
}

@media (min-width: 720px) {

    .banner img:nth-child(1) {
        grid-column: 1/2;
        grid-row: 1/3;
    }
    
    .banner img:nth-child(4) {
        grid-column: 3/4;
        grid-row: 1/3;
    }
    
}