Overwriting styles of MenuBar doesn't take the required effect

[ms83]

Hi,

I wanna do something simple. Just overwriting the MenuBar's skin styles with my own. But I'm not sure where's the right location to put my styles in.
Here are the code parts:

var homeMenu = isc.GFMenuButton.create({
                ID:"homeMenu",
                pageID: 'index',
                title:"<spring:message javaScriptEscape="true" code="GUI.head.title.home"/>",
                targetURL: "<c:url value="/index.html"/>",
                isRoot: true,
                styleName: "PNmenuButton"
            });


var menuPane = isc.Canvas.create();
                menuPane = isc.Menubar.create({
                ID: "menuPane",
                autoDraw: false,
                overflow: "hidden",
                menus:[homeMenu]
            });


isc.VStack.create({
                ID: "navStack",
                width:"95%",
                height:20,
                position:"relative",
                top:20,
                members: [menuPane]
            });

As you can see I've added my css class in the MenuButton but this only takes effect on the sub menu items but not on the primary menu item.
Adding the styles to the MenuBar takes effect on the whole MenuBar.

Maybe someone can help me. Would be great.
Thanx!

(SmartClient version used: 8.1; browsers used: IE 8, FF 8.0.1)