Just for simplicity I’d also suggest three simple design principles, as I had commented elsewhere earlier:
- There are 7 basic default block styles: H1–H4, checkboxed, bulleted, or numbered
- All of these can be additionally marked up with either “highlight” or “callout” styles
- all of these can be toggled with a right-click on the block selector, as I suggested here.
=> that would be consistent, memorable, flexible, and practical.
I suspect this would also be easier to learn for users and to maintain and document for the team.