I use the Xenea theme on my site, and noticed a couple of CSS errors in the theme.
Specifically, header.html was missing units in one case, and print.css specified an auto padding in several places (which is not allowed).
Also, there were many instances of uppercase element selectors, which would stop working when (if) PGV gets around to properly supporting XHTML.
After that, I went through the whole lot with a fine-toothed comb, optimising CSS rules, fixing other little things, including moving several IE and Mozilla-only styles in style.css to their respective browser-specific files.
It would have been nice to do something about the url() font-family, but I'm not sure exactly how that's being used by PGV.
Attached is a ZIP of the files that I've changed.