I believe that it would be a simpler and cleaner UX if you simply had openEHR as the home view, and had a simpler categories page that people can visit via the top and/or sidebar navigation if they choose to (likely to be a fringe activity):
Thanks @Nathan - happy to get some other views of the community on this, my own feeling is that openEHR users do like to be able to see the categories and the sidebar view of categories is only a partial list (which lets users set up their own sidebar contents).
We do have a lot of categories in this forum, this was the way it was set up before my involvement, but this may reflect the global and somewhat complex nature of the standard.
I don’t which we have any immediate need for a banner, although perhaps a search banner which makes site search more prominent might be of use for new users.