Making the Library, Page Info and cia. windowses respect set GTK theme on Linux?

[Impeta]

Title says it all. Is it possible? Couldn't find an option related to it off UserChrome nor user.js. For visual reference, I want these;

Not these, which they came with when I got the Photon style.

[black7375]

You can set userContent.page.proton to false

[Impeta]

Doesn't seem to work. Tried "Clean startup cache...", no dice either.

[black7375]

Oh, I made a mistake.
Since it's about the browser window, you need to disable userChrome.theme.proton_chrome

[Impeta]

Oh that worked! Thanks!
Though another thing I noticed is the drop down menu off "Organize", "Views" and "Import and Backup" still look to default to plain Proton flair (and I assume any other menu off browser window), and I would like it preferably off as well. Can I disable that too or that's the most I bear with right now?

[black7375]

Of course you can.
Try to disable userChrome.theme.non_native_menu