Including a javadoc/scaladoc into grav

I'm creating a documentation for a project. It's written in Markdown and gets compiled to html. It uses paradox and also looks like this http://developer.lightbend.com/docs/paradox/latest/. Is there a way to include such a whole html tree into grav?
For example working with antimatter and if you navigate to the documentation you'll get the whole documentation html tree inside of the page and can navigate the documentation and keeping the antimatter menue header?

Grav won't understand an HTML tree as it's not in the format it's looking for when it comes to processing content (markdown .md pages). However, you can drop an HTML folder into Grav's structure and when you point your browser at a specific page, the webserver will serve that HTML directly without Grav even processing it.