css3 accordion code markup

<article class="ac-container">
    <div>
        <input id="ac-1" name="accordion-1" type="checkbox" />
        <label for="ac-1">About us</label>
        <section class="ac-small">
            <p>Some content... </p>
        </section>
    </div>
    <div>
        <input id="ac-2" name="accordion-1" type="checkbox" checked />
        <label for="ac-2">How we work</label>
        <section class="ac-medium">
            <p>Some content... </p>
        </section>
    </div>
    <div><!--...--></div>
</article>