How to change style of drop down list?

I able to change the font size for dropdown box (where we select values) in the following way:
dropDownList.setStyle("font-size","7pt");

Also tried:
.aw-list-item{
font-size: 7pt;
}

But this is not effecting the style of text of the drop down that is visible to us after selection.

Can someone help me change the style of dropdown visible to us after selection?