only style for the drop down in bootstrap.css -

i have created site in yii , have added bootstrap down down in web page ,almost whole , feel of site have changed style drop down menus bootstrap.css.is there css available there style drop down available.so can customise drop down wish. http://www.w3resource.com/twitter-bootstrap/dropdown.php have completed first drop down of tutorial , dont understand how can customise it

in customize section think can select need in order avoid adding unappropriate css or js file.