Ask almost any front end web developer: once you get deep in a complex, ongoing project with a lot of CSS, unused selectors can be a problem. We’re naturally inclined to keep on bulking up our projects with cool CSS3 transformations and responsive media queries, but it’s decidedly unglamorous to prune what’s no longer needed.
That what makes this little Firefox plugin such a good start. It’s far from comprehensive – you only can really search for unused selectors in the immediate scope of the page you’re on – but it has come in handy.