Ask HN: Is there any tool for testing a site's CSS specificity etc..?
... so that you can get a break down of results like the ones shown here:
http://www.csspurge.com
You can find unused CSS with https://github.com/giakki/uncss and linters, e.g. https://github.com/brigade/scss-lint/, will analyze and warn if the complexity (number of levels etc) grows too big.