Dark navigation icons for custom backgrounds

[Tealk]

There should be a possibility to darken the navigation icons for own backgrounds

A separate background, the upper edge is bright
Theme Color #078D4E

Unfortunately I don't know how to get the navigation dark like it is with some of the preinstalled background images.

Originally posted by @Tealk in #33925 (comment)

[skjnldsv]

Allowing to select a different colour with the background should let you do this.
Closing for #34560 (comment)

[Tealk]

@skjnldsv I'm not sure if we are talking about the same thing, I just want a switch that turns the icons black, then they would be easy to read.

If you use the user backgrounds, the icons on some light backgrounds also turn black.