So there's a problem on showing sign colors. Other players on server say they have no problem seeing colors, but being in a minor group of Mac OSX users, I think problem could be on OSX side.

Problem is show in pictures, if you're in correct angle, you can see the colors, but when looking from straight ahed (+- 30 something degrees), colors disappear.

Screenshots are taken using Resource Pack (no client side mods), but I have tested with straight Vanilla client with out any mods nor Resource pakcs, still same problem.

Also the version is 1.7.10, and has been there (at least for me) for many versions (from like 1.6 or so)

Edit: Problem also present in vanilla server, vanilla client