How do I modify the "topic" skin in WebHelp?

Basically, I'm trying to find a way to have a feature that I had in MadCap Flare. They call it "Master Pages", but whatever you call them, I need them.

The idea is that I need to have the ability to change the HTML that wraps around any topic generated by RoboHelp in the WebHelp Plus output (but, really, I'd like to do it if I ever generate HTML5, too!). Adding my own custom toolbar with links at the top, a footer, etc, etc. What I want to add is of no importance, really, but I do have this requirement.

So, how is this done?