main {
    display: grid;
    grid-template-rows: auto 300px auto auto;
    grid-template-columns: auto auto auto;

    margin-left: 10%;
    margin-right: 10%;

    column-gap: 10px;
    row-gap: 20px;
}

h1 {
    /* grid-column is a shorthand of grid-column-start and grid-column-end
       the '/' divides where to start and end */
    grid-column: 1 / 4; /* start on grid line 1 and go to grid line 4 */
    grid-row: 1 / 2;

    text-align: center;
}

img {
    grid-column: 1 / 4;
    grid-row: 2 / 3;
    height: 100%;
    object-fit: cover;
    margin-left: auto;
    margin-right: auto;
}

#art1 {
    grid-column: 1 / 2;
    grid-row: 3 / 4;
}

#art2 {
    grid-column: 2 / 3;
    grid-row: 3 / 4;
}

#art3 {
    grid-column: 3 / 4;
    grid-row: 3 / 4;
}

footer {
    grid-column: 1 / 4;
    grid-row: 4 / 5;
    text-align: center;
}

main > * {
    border: 1px solid black;
}