Cross Browser CSS for Flash MX(6)

[COLOR=black][FONT=Arial]I need to integrate 2 style sheets into my flash movie for all my dynamic content - all content is loaded separately by an html file into the flash movie. I found this online to use a style sheet into my flash movie [COLOR=#0000ff][/COLOR][/FONT][/COLOR]
[COLOR=black][FONT=Arial]The only thing is it does not work with my dynamic content because the content is not hard coded into the flash action - so I need to know how to apply two style sheets to all dynamic content in my movie and also detect if the user is on a mac or pc then load the appropriate style sheet.[/FONT][/COLOR]

can you help?