Firefox 57+ (Quantum) and Vertical Tabs

As you probably noticed with Firefox 57 codenamed Quantum a lot has changed – plenty of extensions are now not working.

However one of the things I found particularly annoying was that while I was using the vertical arrangement of tabs using extension such as Vertical Tabs Reloaded (Tree Style Tabs doesn’t seem to work atm) the tabs were effectively doubled – one on top and the other one showed on the side – definitely not as intended.

Solution? Open the profiles directory (if not sure where is it just open in explorer %APPDATA%\Mozilla\Firefox\Profiles\ ) and then open the subdirectory with your profile (some random strings) and here create a folder named chrome (it’s where other plugins have their folders such as adblockplus ghostery and others) within this folder create a file named userChrome.css and inside copy/paste following code:

#tabbrowser-tabs { visibility: collapse !important; }

That’s it – close Firefox and reopen it – the horizontal tabs are gone for good.