Im having a problem with word spacing, mainly with Firefox. On mac the text spacing is fine but I had to put a word spacing of -2px to achieve the same affect in Firefox on a PC. Now the word spacing on mac looks too close!
Fonts are always going to look different cross-browser. Even more so when you’ve got different operating systems involved. The best you can hope for is "close".
I think what the doc ment is there really isn’t a way to control cross OS issues, just get it as close as you can where say the mac looks good and either just forget pc, I dont think anyone will know the difference unless they use both mac and pc, or comprimise between the two.