.gallery {
    display: grid;
    grid-template-columns:repeat(3, 32.8%);
    grid-auto-rows: minmax(100px ,auto);
    grid-column-gap: 0.3%;
    grid-row-gap: 0.2%;
    justify-items: stretch;
    padding-bottom: 1%;
}

.gallery > div {
    margin: 5px;
    box-shadow: 5px 5px 5px grey;
}

.gallery > div > img {
    width: 100%;

    /* Resize images */
    height: 100%;
}

.gallery > .big {
    grid-column: 1/3;
    grid-row: 1/3;
}
.gallery > .double-row {
    grid-column: 3;
    grid-row: 1/3;
}
.gallery > .double-column {
    grid-column: 1/3;
}

/* Optional Option */

/* Other Column Double Row */

/*

.gallery > .double-row-two {
    grid-column: 2;
    grid-row: 1/3;
}

.gallery > .double-row-one {
    grid-column: 1;
    grid-row: 1/3;
}

*/