Consistent UI/UX guidelines throughout the Browser

[VimYoung]

I could post it in "Ideas" section but I found that section bloated and more importantly I would love suggestions from you on the topic in a more general sense.

Zen doesn't compromises on its look (obviously) , but it also provides much needed things which always lacked in firefox, I just thing that this aesthetic look and feel should be extended further and used in secondary popups/sections of browser.

I mean as long as I open sections like bookmark manager(Ctrl+Shift+o), history manger(from triple dots > History>) , Downloads section, About Zen etc from the drop down on top right, the UI changes to basic/native, these popups open in native window decorations and probably in native UI too(in linux), this feel odd and old.

It would be more satisfying to have these managers/popups in the standard UI guidelines which Zen follows and also enable the Look And Feel color settings in them. I am not aware that they are implemented before in any firefox derivative but it will be good to have.