article {
        padding: 10px;
        margin: 10px;
        background-color: lightgray;
        height: auto;
        min-height: 10vw;
        width: auto;
        min-width: 10vw;
        display: flex;
        justify-content: center;
        align-items: center;
    }

    section {
        display: flex;
        flex-direction: column;
    }

    @media screen and (min-width: 750px) {
        section {
            flex-direction: row;
            background-color: lightgoldenrodyellow;
            justify-content: space-around;
        }
    } 

    <section>
        <article>
            <h2>First</h2>
        </article>

        <article>
            <h2>Second</h2>
        </article>

        <article>
            <h2>Third</h2>
        </article>

    </section>