Select

<div class="b-form__group">
    <label class="b-form__label" for="select-dd">Select drop down:</label>
    <div class="b-form__select">
        <div class="b-form__select-arrow"></div>
        <select class="b-form__select-select" id="select-dd" name="select-dd">
            <option value="" disabled selected>Please choose an option, this is truncated to look amazing</option>
            <optgroup label="Option group: I">
                <option value="1">1</option>
                <option value="2">2</option>
            </optgroup>
            <optgroup label="Option group: II">
                <option value="3">3</option>
                <option value="4">4</option>
                <option value="5">5</option>
            </optgroup>
        </select>
    </div>
    <span class="b-form__message"></span>
</div>