To re-state the problem: the inline-block property on the <li> tags was adding a space when rendering the nav-menu-template in Firefox 21.0. I wanted the list elements to meet with no space between them, and the normal methods of setting margin and padding to 0 did not work.
Is it a better solution to use some menu plug-in? I am learning WordPress and gladly accept your never, ever injunction, but I can’t be the first person to encounter this problem, either. Is there another solution?