No matter what I do I cannot seem to make the dynamic menu background anything other than white. I have tried setting every single background attribute to Transparent both via the markup attributes and using CSS but no luck.

When I view the page source I see that the following inline style has been created:
.ctl00_Menu1_0 { background-color:white;visibility:hidden;display:none;position:absolute;left:0px;top:0px; }

No matter what I change this style's background-color seems to be fixed on white.

Any help would be greatly appreciated!

can you show the menu control html source and your css file related to the menu control?

if not miss taken the one you gave at began it is has assigned by default.

background-color:white;visibility:hidden;display:none;position:absolute;left:0px;top:0px;

I still haven't find the way to clear it

What does your menu definition look like? Can you set the BackColor through the ASP.NET style attributes?

Example:

<asp:Menu runat="server" BackColor="#A2ABB0"

... 

Okay here is my code. I had to escape all the greater than less thans to make it friggin post properly. Is that normal? Anyways, on with the show:

A co-worker just pointed me towards a very helpful website, http://www.pastey.net/

So, in an attempt to redeem myself and make this thread a bit more helpful/readable, here are links to my ASP and CSS code on Pastey.net

I ran into this same problem before and I unfortunately couldn't figure it out either.  Trying to specify a background-color though a stylesheet for the dynamicmenustyle by setting the DynamicMenuStyle CssClass property never seemed to work.  It would work with every other style on the menu, but not the DynamicMenuStyle. 

I just had to workaround it by specifying the actual DynamicMenuStyle BackColor property directly instead of through a class style, which luckily worked for my situation for now, but I understand the frustration and it would be interesting to know why this doesn't work. Almost seems like a bug that someone accidentally left that it always outputs the same style.

The ASP.NET Menu control automatically adds several styles to the embedded header style.  For example:

..ctl00_ucMenu_MenuCBM_0 { background-color:white;visibility:hidden;display:none;position:absolute;left:0px;top:0px; }

The culprit is an internal method of the Menu control called EnsureRenderSettings.  It calls this.Page.Header.StyleSheet.CreateStyleRule() 
several times, adding style rules to the embedded stylesheet.  EnsureRenderSettings is called at the beginning of the Menu's OnPreRender 
method.  Hey, we can override OnPreRender!  That means we're getting closer to an answer, right?  Right, but if we override OnPreRender 
and don't call the base implementation we'll be missing out on some important functionality.  This uses internal methods so we cannot 
emulate it in our override.  

The solution is a bit of a hack, but it's quick and direct.  We override OnPreRender and after calling the base implementation as normal, we 
clear the embedded header styles that were just added.  Add this to to your menu adapter (or derived Menu):

using System.Reflection;
using System.Collections;

protected override void OnPreRender(EventArgs e)
{
    base.OnPreRender(e);

    // Clear the embedded header styles that ASP.NET automatically adds for the menu
    ArrayList selectorStyles = (ArrayList)GetPrivateField(Page.Header.StyleSheet, "_selectorStyles");
    selectorStyles.Clear();
}


/// 
/// Gets the value of a non-public field of an object instance.  Must have Reflection permission.
/// 
/// The object whose field value will be returned.
/// The name of the data field to get.
private object GetPrivateField(object container, string fieldName)
{
    Type type = container.GetType();
    FieldInfo fieldInfo = type.GetField(fieldName, BindingFlags.NonPublic | BindingFlags.Instance);
    return fieldInfo.GetValue(container);
}



It accesses the private member _selectorStyles using a little reflection.


Rebuild your application and you should be good to go.  The embedded style in the header is gone.  Hope this helps!


(P.S. Lutz Roeder's .NET Reflector was instrumental in allowing me to easily track down the problem.)
(P.P.S.  I had to surround my post in 'pre' tags, too, because the Compose tab won't automatically format anything, even line breaks.  I guess 
they just don't care about Opera users.  This will definitely keep me from being an active member of the community.)