Text rendering and web design in Windows, OS X, and Linux

[tinypaperhat]

Hey, I'm having trouble with some of the sites I have developed and the width of the text rendered by different operating systems.

For instance, a menu can look fine in Windows and OS X in all browsers. Then in Linux, on the same browser, it shows larger text even though it is the same font family and size. This normally doesn't matter, but in areas like menus it can push elements out of their containers.

Are there design guidelines or rules that can force this variable sized text fit in a menu that is say, 900px wide?

At this point I am considering using php and $_SERVER['HTTP_USER_AGENT'] to check the operating system and set a different css file as needed. If I do this, should I have to check each distro of Linux for different text rendering issues, or will it be pretty much uniform for the Linux kernel?

Is this a good/common solution or is there something I am missing design-wise that can help me with this problem? Thanks.

[knorthfield]

Make sure you are using a decent CSS reset. Yahoo has a good one. http://developer.yahoo.com/yui/reset/