Hide the outer dividers on a Centered Top Bar.

TopBar Tips

When Top Bar is in centered mode, the divider lines to the left of the first menu item and to the right of the last menu item can be unsightly.

The following CSS snippet will hide them.

.top-bar-section ul .divider:first-of-type, .top-bar-section ul .divider:last-of-type{
border:none!important
}

This code is best added to the site wide code in RapidWeaver, that way it will apply to all your pages. Of course if you only want to alter a certain Top Bar page then just put it in the page inspector CSS