DropDownList backcolor only on first item??

Hello. I dynamically build a drop down list inside of a datagrid that I want to apply a backcolor to. Right now I'm applying the color to the entire dropdown, but is it possible to apply the color only to the first item in the drop down list? I will always want only the first one highleighted regardless of what name/value pair happens to be the first item. It would look nicer than having the entire thing colored when expanding the list

Here is how I'm building the list:

ddl.DataSource = ds;
ddl.DataTextField = "product_shortdesc";
ddl.DataValueField = "pproduct_id";
ddl.Visible = true;
ddl.BackColor = Color.Yellow;
ddl.DataBind();

thanks in advance!!