At http://olddogstudios.com.au/dev/
The menu is two tiered with Darren Hoyt's solution and the CSS sliding door solution provided by Jean-Baptiste Jung.
The problem is that in the secondary menu, when you click "Clients" or any other menu with a sub menu listing, the left side of the tab from the top menu shows when hovering.
I need a solution to remove this so the secondary shows as text. I am happy with the top menu as it is, but it is the secondary menu that is the issue.
I look forward to your solution.			
Kannan Sanjeevan answers:
								Add for the following code at the end of your stylesheet
#mainmenu #subnav li a:hover, #mainmenu #subnav .current_page_item a, #mainmenu #subnav .select a {
background:none!important;
} 
Nile Flores comments:
Bingo!!!
Nilesh shiragave answers:
								Just add 
#subnav li:hover,#subnav li a:hover
{
background:none !important; 
}
in your themes style.css file							
Nile Flores comments:
applied, but no use.
Nilesh shiragave comments:
										Add that at the bottom of your style.css
#subnav a:hover, #subnav a:active,  
#subnav li.current_page_item a,  
#subnav li.current_page_item a:visited,
#subnav li:hover,#subnav li a:hover {  
 text-decoration:underline;
background:none !important;  
     }