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/