[css] Changing the background color of a drop down list transparent in html

I'm trying to change the background color of a drop down list in HTML to transparent.

HTML

<select id="nname">
  <option value="volvo">Volvo</option>
  <option value="saab">Saab</option>
  <option value="mercedes">Mercedes</option>
  <option value="audi">Audi</option>
</select> 

CSS

#nname {
    padding: 5px;
    color: #000;
    font-size: 12px;
    background: transparent;
    -webkit-appearance: none;

}

however, the background stays white and the text stays black. Any ideas?

Or maybe

 background: transparent !important;
 color: #ffffff;