Is there a utility that will take a css file (or possibly several) and compare it with one or more html files giving a report
  1. css usage in each html file.
  2. undefined css in html file.
  3. unused css in css file.

So the output might look like

#someting defined in first.css used in a.html, b.html c.html
.otherthing defined in second.css used in b.html
….
#snafu undefined, used in c.html
….
.toomuch unused defined in first.css