@pcwacht
Thx for support. I think we are in the same direction ...

And for wb it would be indeed a very big chance to doing it.
@Stefek
Once more same direction

Indeed. Exactly that's the way to do it!
But to be honest: Based on the experience with the new backend theme this IMHO only really makes sense with(!) little support of the development team

The problem to style this special page on the backend is, that the code is hard coded by php (very old code from the beginning of the cms, someone reported from about the 80th). And the modules in the html code are not separated which makes it very hard and could not be a very special work only (i.e. spaces or placements in the inner of the module area can not be set).
>>> But: The solution could be very easy:
A workarround without writing module code output completely new (which indeed is not possible for the team at the moment) would be to ad the output of an simple div-container arround any module-output with some special classes (i.e. class: module-area, maybe(!) if not to much work class with module-name).
>>> Chance:
This could be done for 2.8.4 with very little engagment as it is a very small and neutral changing of the code output and without risk as neutral divs does not affect working code.
>>> Situation:
The development team especially the responsible member for the core in the german forum made VERY CLEAR that there will not be done any changes on the output code (as writing backend templates in later future wb versions will become very easy so bakcend development is not necessary to this up to now).
>>> What could be done:
Nothing is fix and maybe someone is able to change his mind. Even if there are a lot of supporters for this idea - maybe the development team changes their mind.
Possible realisationIn this case I would be on board: as the first step I would do the basic and adapt the new backend theme to 2.8.4 so it could be used up from the mostly beginning (I don't know the actual timing ... three month, one year

actual they are working on next SP for .3 I believe). Then we could do a team to define standard elements and add it step for step to the template. Someone does the documentation ...
... and step for step a little team could improve wb a lot without need of wb development team.
Ok, - to start a little coming up of the development team would be needed. That could be the most difficult thing I am affraid.
So: the question is: Are here ...
... some more who would support the idea?
... some who would like maybe to engage themself?(Especially help on documentation would be very helpful. Maybe the new wiki could be a good/right place for it.)
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NOTE: Just to be sure. Don't be anxious. As the layout works up to now the modules do not have to be change if the maintainers don't like it.