First of all, this is a beta version, we're still testing it.
This tool checks your website for unused CSS selectors. It follows internal links on your website recursively and looks on multiple pages.
NOTE: the stylesheets are extracted on the first page only. The tool does not re-extract the styles from your other pages.
Currently the tool is only 200 pages deep, we're still testing it and will increase the limit shortly. Half of the work is done on our server's side (we can't do everything on the client-side because of the CORS limitations), so please don't abuse it. Results are cached for 24 hours, please be patient. If you see a flickering iframe at the bottom of the page it's OK, your pages are being (somewhat) loaded into it. We'll remove it after testing is done. Frankly, we are just testing the concept and if there's enough demand we'll keep developing the tool further and even post the sources on Github. Send your bug reports to @jitbit on Twitter.
The tool might show pseudo-classes as unused, like
:focus. Obviously because it was unable to find any "hovered" elements on the page.
Actualy, before removing any "unused" style form your css-file, double-check that it's really not being used :)