Not need the UI changes:

[BANZOM]

How to revert this UI changes?
I want the webpage to be show on whole screen, it looks like having a padding from all sides...

also a request if you can add comments in user.js file

[prirai]

Hi

You can change it from your side by going into your own user.js and changing privacy.resistFingerprinting.letterboxing to False.

When it's set to True (which it is), it changes the browser window to the most used screen ratio ie. 16:9 so as to reduce fingerprinting based on screen resolution.

Hope that helps, I'll put in the required comments also in the user.js