ASP.NET 4.0 Menu - How to control rendered ouput

Hi, I've specnt a day experimenting on this and am none the wiser. Your help is appreciated.
I am using ASP.NET 4 Menu control and I have tried styling it using both techniques (but not at the same time as this is not recommended) i.e. :
(1) ASP.NET e.g.
<StaticMenuStyle BorderStyle="Solid" BorderWidth="1px" />
And
(2) CssClass e.g.
. StaticMenuStyle
{
      /*my css rules here . */
}
When I view the rendered output source in a Internet Explorer I see the following code in the HEAD section:
<link href="App_Themes/MyTheme/stylesheet.css" type="text/css" rel="stylesheet" />
<style type="text/css">
 /* <![CDATA[ */
 #Menu1 img.icon { border-style:none;vertical-align:middle; }
 #Menu1 img.separator { border-style:none;display:block; }
 #Menu1 ...