Bootstrap 3 uses the .form-control
class to style form components.
<select class="form-control">
<option value="one">One</option>
<option value="two">Two</option>
<option value="three">Three</option>
<option value="four">Four</option>
<option value="five">Five</option>
</select>
http://getbootstrap.com/css/#forms-controls