Space Between Menu Tabs

I have a customer who doesn't like the "gap in tabs" on the menu -- see where the black shows dark blue to the left and right of the item being hovered over. The site is: http://www.youdeservetobehappy.com -- if you want to see, though I don't think it's unique to me. Can you tell me what stylesheet element might allow me to reduce or eliminate the gap between tabs? Thanks, Anne