It has confused me for several days. No matter how hard I rewrite the codes, it seems never compassionate to me.
Google it as "No show asp:Menu StaticHoversSyle", still can't get appropriate answers.
Fortunately at last, Google it with the key word ".Not4.0". I got it.
It should be a bug. The styles can be work only when the menu control's "RenderingMode" property has been set as "Table".
Example codes:
<asp:Menu ID="Menu1" RenderingMode="Table" ...>
<StaticHoverStyle CssClass="staticMenuhover" />
...
</asp:Menu>
References:
http://stackoverflow.com/questions/2655377/how-to-style-an-asp-net-menu-with-css