body {
    background: #EEE;
    font-family: sans-serif;
}

#container {
    --elementHeight: 5vh;
    display: flex;
    flex-wrap: wrap;
    > div {
        min-height: calc(var(--elementHeight) * 5);
        min-width: 50%;
        > div {
            background: linear-gradient(lightgoldenrodyellow, gold);
            height: var(--elementHeight);
            margin: 0 auto;
            width: calc(var(--size) * var(--elementHeight));
        }
        &:first-child {
            min-height: fit-content;
            text-align: center;
            width: 100%;
        }
    }
}

button {
    font-size: 2rem;
}