Feature Request: Rework of colors

[ErikKoppenhagen]

The colors are too similar and are missing a documentation. Sometimes an element (a assume it's an overview or sub-overview) is just blank.
I would prefer a rework of the color scheme (including the overviews) to have an actual idea how deep in the tree you are. Additionally, a legend of the mapping would be great. This even could be used to customize the color scheme.

Here you can see a draft for colors I made on the fly:

[NiklasRentzCAU]

I intentionally designed the colors currently that they all have the same hue and saturation so they do not 'hurt the eyes' when looking at and so that texts are easy to read on that color. In the draft colors for example the feature greens and some other colors just pop too much into view and for example the blue for bundle categories is quite dark and makes the text harder to read.
The colors might need a redesign though to better show which elements belong together.
User-defined colors and/or a legend are a good idea though.