<form class="form grid">
    <div class="grid__row grid__row--padded">
        <div class="grid__col grid__col--xs-12 grid__col--sm-6">
            <label class="label" for="superhero-fav">
                Who's your favorite superhero?
            </label>
            <input class="input" type="text" id="superhero-fav" />
        </div>
    </div>
    <div class="grid__row grid__row--padded">
        <div class="grid__col grid__col--xs-12 grid__col--sm-6">
            <input type="submit" class="button button--primary" />
        </div>
    </div>
</form>