As we sort of came to accept as an axiom - the heading fonts for any document should be arranged in an hierarchy, and the hierarchy font choices should make sense and match.
I have a design that looks something like this:

Clicking on Item One opens an Item One tab with the heading hierarchy presented.
Without going into discussion on the validity of the design (but please, by all means, do point it out if you think it's important) - how one would arrange the heading hierarchy?
It seems to me that it should include the tabs (on both sides) as well, since they serve as headings in concept, but then I have too much - 5 (or 4 if you think that both tabs should have the same styling - which I do).
Any ideas?