Exporting a survey to printable PDF is easy, from "queXML PDF export" I get a zip that contains pdf-file. I can also set some styles, like putting color: red; on td.questionTitle. But how to change font size, color etc. on a radiobutton choise? By reading the source I guessed td.responseLabel or td.responseText,  but neither worked.

Just pinging this one. I try to read application/libraries/admin/quexmlpdf.php but no luck. Can someone confirm, that this is impossible?

It seems that application/core/QuestionTypes/...php -files contain nothing about pdf settings, so all the settings are defined in quexmlpdf.php.