Do I need to consider the Client OS when testing websites?

I have a general web question.

To be able to test my website on various browsers properly, do I need to consider the op开发者_运维技巧erating system too? Is it enough to just test my site on FireFox 3, for example, or do I need to test it on FireFox 3 on Windows, Mac, and Linux? Is it possible for a given browser version to behave differently on different platforms?

I'd say yes, well platform at least.

Some other differences between Mac OS X and Windows (don't forget Linux)

• different gamma levels
• font rendering
• fonts installed by default
• size of the chrome

I realise testing on all OS's can be difficult, so make use of BrowserShots.org.

Yes it is. In fact, I believe firefox on Linux and on Windows actually do display things slightly differently (as for some reason their default font is different)

To be completely thorough, yes - you should be testing on all OSes

Yes, not only is it possible, it's absolutely true. Firefox renders quite differently on, say, Ubuntu than it does on Windows or OS X. While the OS itself is not, strictly speaking, an element, every browser--even the same family--is different for each OS.