Tools to optimize (remove redundancy and merge) CSS? [closed]

Answer 1

I don't particularly understand what you mean by "clean unused CSS", but in any case, I'll throw two tools at you, and maybe one will work (the good ol' shotgun approach).

CSS Lint seems to point out "duplicate properties". There are a range of articles covering some of what it does. But a test with the two definitions you had,

a { color: #fff; }
a { color: #000; }

it didn't do much of anything. While ...

Code Beautifier did combine the two selectors, opting for the latter of the two (i.e. the style that's actually applied). Resulting in:

a {
  color:#000;
}