grid2.css

ul {
    list-style: none;
    display: grid;
    grid-gap: 0.4rem;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    grid-auto-rows: 28%;
    grid-auto-flow: dense;
}

.wide {
    grid-column: span 2;
}

.high {
    grid-row: span 2;
}