One year later, I'm trying the same thing but with the MetroTouch skin.
In the attached image you will see two identical menu bars. (latest 2015 release of ASP.NET AJAX)
They include PNG images 40 px high.
The top one uses MetroTouch skin.
The bottom uses Bootstrap.
As you can see, the border for Bootstrap has gone away per the original CustomClass markup provided in the previous posting.
However, the intended skin is MetroTouch because I am targeting a touch device and like the spacing.
I know there are a few differences with the touch controls. I would like to make the borders go away, as above. In other words, the blue around the three menu items.