[Solved] Help making transparent background of 'about:' pages

Testing in Firefox Beta Hi, I had the code to make 'about:' pages (preferences, add-ons) background 'transparent', but with new Firefox changes that code don't work anymore, and I can't find the way to make transparent again, I tried with all the selectors I can but don't work. I enabled browser.tabs.allow_transparent_browser for this purpose, I made them transparent to show the image behind. I would like to solve this issue or maybe is a issue of 'browser.tabs.allow_transparent_browser'