The ASP.NET Menu controls in my application display correctly in all browsers but Apple's Safari and Google's Chrome.  After researching the problem this afternoon, I'm documenting the fix I used.

ASP.NET Menu Control Renders Correctly in IE, Firefox, and Opera

ASP.NET Menu Control Renders Incorrectly in Safari and Chrome

The Fix:

1. Create the following PageBase class which inherits System.Web.UI.Page and define a Page_PreInit method which contains the fix:
   
   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Web;
   namespace MyProject.WebSite
   {
       public class PageBase : System.Web.UI.Page
       {
           protected void Page_PreInit(object sender, EventArgs e)
           {
               // This is necessary because Safari and Chrome browsers don't display the Menu control correctly.
               // All webpages displaying an ASP.NET menu control must inherit this class.
               if (Request.ServerVariables["http_user_agent"].IndexOf("Safari", StringComparison.CurrentCultureIgnoreCase) != -1)
                   Page.ClientTarget = "uplevel";
           }
       }
   }
   
   
2. Change ALL of your webpages to inherit from your new PageBase class instead of the usual Page class.  It's easiest to do a global replace of ": System.Web.UI.Page" with ": PageBase".  Unfortunately, you can't just add the fix to your Master Page, it doesn't contain a PreInit method as it's a web control not a web page.

Alternate Fix: