Not sure if that helps you:
Did you have a look for the style.css in /dw2pdf/conf?
Maybe I'm wrong but I think you could use this file for your purposes.
* Do not edit this file. Instead add your own styles in
* lib/plugins/dw2pdf/conf/style.local.css or create your own template
* to make sure they are not overwritten by updates
HTH
Regards Karl