Well, the style of the dropdown is vendor specific. So you need to change it for all of them. See,
<asp:dropdownlist id="NewDropDownList" runat="server" width="136px" cssclass="ddl" onselectedindexchanged="jobRun_SelectedIndexChanged" autopostback="True" xmlns:asp="#unknown"></asp:dropdownlist>
.ddl{
width: 268px;
padding: 5px;
font-size: 16px;
line-height: 1;
border: 0;
border-radius: 5px;
height: 34px;
background: url(http://cdn1.iconfinder.com/data/icons/cc_mono_icon_set/blacks/16x16/br_down.png) no-repeat right #fff;
-moz-appearance: none;
-webkit-appearance: none;
appearance: none;
background-position-x: 244px;
border:solid 1px #ddd;
}
The bold text is important. :)
One quite good demo is
here[
^].
-KR