[GB 2.0 pre alpha] Color separation of active panels

[quantumleap33]

Description

In the block editor at the settings on the right, I have noticed that sometimes hard to distinguish when the active panel ends and the following one starts visually especially when the active panel and the one after it are both open. There is only a light bottom border to separate them. Not sure if it's possible but wouldn't than be nice if the active panel's background color was a light color other than white? The blue border could actually go as well.

For example, this active but closed Effects panel:
https://i.imgur.com/YDxeVMP.png

could could become like this:
https://i.imgur.com/psc90SV.png

And the same active and open Effects panel:
https://i.imgur.com/ikgAu04.png

could could become like this:
https://i.imgur.com/TZYD1qE.png