Add dark mode support for gin

jan kellermann → made their first commit to this issue’s fork.

Then please have a look and give feedback :)

We added classes for gin but also for general dark mode without gin as admin theme.

Well, that looks much better than before.
It would be nicer, of course, if the background color of the circular icons could be adjusted when the values for dark mode are applied.

That would make the widget look much rounder.

What I also noticed is that the Duplicate entry created by ECA does not have an icon. Here, you could consider implementing a generic icon for such cases, but that should be the subject of a separate issue.