add a css page?

Hi,
I see that gallery looks for it's own two CSS pages...
Since CSS uses the last instance down on a page, is there a way to insert my own custom CSS page into the gallery pages?

So that gallery uses it's own css files, and then a link to mine (one folder back) comes up next? Just not sure what file to put this code into.

I'd like to edit more info in the "head" tag as well, but can't find where to do this. (Not the header html_wrap files, those just start at the body tag)

Any help is appreciated...thanks.