Finally found this perfect webpage styler that I have searched for hours with multiple change attempts in the about:config with no success until now! Really needed this on my 21:9 Ultra Widescreen Monitor! Thanks heaps!

Sells user data, website is basically dead

Good, but site is often laggy. And why you would want this extension on Firefox anyways? There is userContent.css!

spyware

Developer abandoned the extension and added spyware to record your browser history. Use Stylus instead: https://addons.mozilla.org/en-US/firefox/addon/styl-us/

Use stylus instead

spyware

Please respect user's data!

DO NOT INSTALL, this is spyware and it hogs all your CPU!!

Data collecting company, can't believe that firefox still allows their app here... (Everyone who reads this, please report this addon for abuse!)

Massive violation of privacy.

dont use its spyware.

Allows you to customize websites, BUT there is a catch... It has spyware. If you don't know what spyware is, its a virus that, well, spy's on you and tracks you. This extension will steal your browsing data and sell it to other companies.

There is a similar extension called Stylus, which is basically the same as this but it does NOT have spyware. The link to the extension is: https://addons.mozilla.org/en-CA/firefox/addon/styl-us/