mainly in navbars, where we were doing custom
things that bootstrap already did with classes.
This did require the removal of multiple class LESS inheritance for
navbar buttons, because it doesn't work properly. Seems like a LESS bug, but I'm not sure.
For all of the discussion that we had about what kind of icons should
and should not be used to indicate what mode the notebook is in, we
never went through to make it possible to override it.
With this change, it is now possible to override what icons are
displayed for Command and Edit Modes.
For example, @minrk liked the fighter-jet icon for Command Mode, so he
can put this in his custom.css
.ipython-command-mode:before {
content: "\f0fb";
}