Too funny, it works in 6 and 8 but not 7, and in FF 2 and 3.6, but not your version? Ahhhhh... the joys of CSS. What version of FF are you running?
The default settings of my editor are set to no BOM, and usually it's not a problem, but occasionally I find files like this where I have to yank it. I'll fix that with the other mods.
And thanks for the heads up on the conditional comment. One of the great things about master pages is that you can group things more logically in the content page, but it means you forget their actual order on the page. These are OO-CSS components so there shouldn't be any serious conflicts, but I have switched the conditional comment on my dev box to come after the embedded styles. When I'm finished with the rest of the changes, I'll upload it and test again.