Welcome to the forum.
What your developer has done is edit the output files rather
than the source files. Because of the version differences he would
not have been able to edit the source files. I wonder if you gave
him those anyway or just the output?
Regardless you are where you are. I do hope you have a backup
of the project from before you copied the edited output files back
into the source. It will be easier to start from there and have
your developer advise the changes by some other means. Otherwise
you have a bit of an unholy mess to sort out.
There is a way of cleaning up the output files if you really
have to but given your experience level, you may not want to go
there. If you have no choice, then Rick Stone's site has an
excellent article on the matter and I can let you have the link
later. Not to hand right now.
When you generate your output, RH, creates two versions of
the CSS, one for IE, and one for Firefox, that is the ns one you
are seeing.
Your source project CSS should be the only one you need.
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