Helium is a javascript tool for discovering unused CSS selectors across multiple pages on a web site and it runs from the browser.
Installation
Add a script element somewhere on your site that is loaded into every page that will be tested. This is typically a header or footer section. The element looks like:
Helium is initiated by calling the method “helium.init()”. This has to be placed somewhere on the page where it gets called after page load. An example of this is: