pdf.css makes no visible difference in the PDF export

Unable to style PDF export according to http://platform.xwiki.org/xwiki/bin/view/AdminGuide/Configuration#HCustomizingthePDFexportLook26Feel - either by class/template or pdf.css method.

used CSS from configuration guide, placed as pdf.css into /templates:

h1, h2, h3 {
color: red;
}

And the resulting PDF does not have red headings. Changing xhtml2fo.xsl does have effect (but as it does not effect color of H tags that shouldn't be problem).