Originally Posted by angst
Yes, both my PC & Mac are using the exact same version, but the FF on Mac is rendering differently. I thought they would be the exact same engine. but I guess not.
A link would be really helpful.
I believe I misspoke a little in that the CSS support for FF Win/Mac is exactly the same, but likely there are minor differences in rendering pipelines since they have to use slightly different code bases. Correct CSS code will render the same in both though.
Because of this, I still think the difference you're seeing is related to differences in error-case handling, or differences in how they're handling contradictory or inconsistent CSS usage.
You would really help yourself by sharing your code with us so we can help you, rather than dismissing our instincts of CSS misuse and trying to place it all on browser differences.