[thomasrambaud]

Not using a CSS rule in a single page doesn't mean you don't use it elsewhere => the generated CSS is necessarily wrong.

This tool is useless but being a POC.

[deanclatworthy]

Exactly. I minify my site's CSS but there are rules used on only some pages. Unless you crawl the whole of a website, this tool is useless for any site that has more than one page.

You'd be better off using SitePoint's DustMeSelectors as it at least makes an effort to crawl the site's CSS: http://www.sitepoint.com/dustmeselectors/

(bit out of date though, it seems)

[bazzargh]

Yes, 2.2 is out of date. DustMeSelectors 3.01 is now at http://www.brothercake.com/dustmeselectors/ (or just use the Firefox add-ons search to install it from Mozilla, not a random site)