The lightgray menu border color #ededed introduced in
commit f147e5a66f (by PR #2095)
is way too light for my display (and probably others).
Thus the menus have no clear border which looks odd and broken.
This commit simply darkens the menu border to #bdbdbd, which
coincides with the (current default) color of the menu separator.
Signed-off-by: Stephan Beyer <s-beyer@gmx.net>