Difficulty to edit layout with lots of container and blocks

We are struggling with the shaky layout editing feature in v.9. When you move blocks or edit long pages with sections and containers, your layout looks scattered, moves up and down and behaves uncontrolled. The vertical spacing of areas, layouts and blocks is way too large, making it difficult to find, edit or move your block.

Most of our clients love exactly that editing interface, - actually the reason why they stick with Concrete.

We’re asked to simplify or making it easier to edit pages. Overriding didn’t work, so we came up with using
Events::addListener('on_before_render', function() in /application/bootstrap/app.php and load the modified classes needed.

That works, but I’m not sure if that method is a good way. When I look into the HTML source of the page it shows exactly these CSS styles at the end of the page when logged out.

What would be the best way to override or modify the CSS for the layout mode classes?

Can these classes be customized somewhere else and is there perhaps an improvement underway in a future release?

Thank you for help.

Did you see my Github Issue?

Yes we saw it, thanks Bruno.
We are interested if other users have the same problem and how they solve it.
But it seems that only few people are bothered.

Override does work with application/css/cms.css
Yes, it would be nice to have an extra way of choosing a setting of your real-time display. I hope concretecms is not moving away from wysiwyg.