Testing in Firefox, I get the error:
> Error: The stylesheet http://kompak.mine.nu/wakaba/css/gurochan.css was not loaded because its MIME type, "text/plain", is not "text/css".
> Source File: http://kompak.mine.nu/wakaba/
> Line: 0
Apparently it won't load stylesheets with the wrong MIME type in ultra-strict mode. I guess you should either add that MIME type, or turn off the XHTML stuff (in both config.pl and .htaccess).