Apply CSS To FileUpload Control?

How exactly do I style this control?

I have tried this but it doesn't work.

<asp:FileUpload id="upload_tb" runat="server" />
#upload_tb
{
width: 500px;
}

Also how can I style the browse button that comes with this control? If it is not possible are there other alternatives?

Edit:

I checked the generated source and asp.net gives the control this id ctl00_main_content_upload_tb

I changed the CSS to

#ctl00_main_content_upload_tb
{
width: 500px;
}

but it does not stretch the control. It adds padding to the right of the control.