I would like an 'empty' button at the right end of the page menu bar which fills the page horizontally 100%.
To explain, here is how it looks now:

I tried adding a background attribute to:
echo '<div id="menu1" style="background: #EEEEEE;">';
in bfa_header_config, but then ofcourse the white space between the buttons is gone:

Tried solving that with adding a white border to the buttons on the right side, but because of the space between the buttons this doesn't look nice:

I am sure that what i'm doing is not very 'neat'. But it was getting very late and I was desperately looking for a quick solution. Hopefully some of you came up with, probably a much easier, solution.
Thank you so much in advance.