I'm not a full time developer, but for simple tweaks of CSS I rely on Chrome Tools to let me "inspect" the CSS is finally applied to the selected HTML. I am looking to see if there is any equivalent tool for CSS for print. Is there some sort of IDE that will provide insight to how the CSS is applied? What tools do you recommend for developing for PrinceXML?

Personally I use the browser inspector most of the time and it's fine, the only time it lets me down is when it comes to Prince-specific properties or things related to pagination. Unfortunately I think we would need to create our own inspector tool to solve that problem and it's a major undertaking!

Mike, I'm new at this. What is the browser inspector? Are you speaking of the WEB browser?

Yes I was referring to the developer tools in Firefox.

You can have Chrome emulate Print mode. I do that a lot.

When I'm writing CSS for specific or multiple document sizes, sometimes I use tools like https://sizzy.co or https://polypane.app to make the preview rendering easier.

Try DocRaptor - PrinceXML web service and official PrinceXML partner

If you're on a Mac, there is a free PDF viewer called Skim that can automatically refresh PDFs when they change on disk. You still have to refry the PDF every time you want to check something, but you can automate that as well with Gulp if you like.