B2B CSS, they are almost same, if I need modify, how can I chose.

there are several CSS which contain more or less the same details.

stylesheet.css

stylesheet_ge.css

stylesheet_ie5.css

stylesheet_ie6.css

stylesheet_ie55.css

stylesheet_op7.css

why they create these files which contains almost same details, however, I cannot find which JSP apply which CSS, any suggestion? I am using IE development toolbar, but sometime you can not see which CSS applied to the JSP.

Cheers,

Eric