Support HTML headings up to H6

[druxstr]

The editor only supports HTML headings up to h3.

Users may need to structure documents with h4, h5, and h6.

Not being able to add proper headings causes accessibility issues.

When unable to use headings, users fallback on fake heading (bold text, # headings) that aren't accessible.

[AntoLC]

The markdown conversion is not yet implemented but we can create up to h6 title with the formatting bar:

[virgile-dev]

Hey guys,
I'd like to have @rl-83 (La Suite's Designer) on this before we start a pull request.
How many title levels should we have on Docs? 6 seems a bit much.

[druxstr]

Docs should support <h1> to <h6> as it's standard HTML. Users can expect up to 6 standard headings in many document writing apps. As the UX slogan goes "You are not the user" (2 min video). We can't predict how complex user created documents will be.

Going up to <h6> is also an accessibility feature. Docs targets people that are required to make RGAA compliant documents, and not supporting basic HTML headings will be an issue at some point. This said, toggle headings are a 100% different thing, and I have no clue how many are needed.

[AntoLC]

Hey guys, I'd like to have @rl-83 (La Suite's Designer) on this before we start a pull request. How many title levels should we have on Docs? 6 seems a bit much.

It already in production, it is a Blocknote feature.

[rl-83]

The challenge of working on an application aimed at a broad audience like Docs is finding the right balance between complexity and ease of use.

Accessibility has been cited to justify the use of six heading levels. I would like to contest this, as there is a risk that the repercussions of usage could actually degrade accessibility, in addition to the overall experience. Your video "You Are Not the User" unfortunately serves as a good example of this. We tech-savvy individuals know how to use six heading levels properly. But what’s to say that a casual user won’t mix up headings of different levels, confusing levels 3 and 4, or using just levels 1, 3, and 5 to create more size variation between headings, or implementing some other odd structure? What happens if multiple collaborators adopt different heading structures? There are many other weird usage scenarios we expose ourselves to by allowing so much flexibility in heading levels. I'm afraid can quickly lead to documents that may be difficult to read in an outline format or, worse, for a screen reader. Giving users freedom can be good. But I am convinced that giving too much freedom, without carefully studying needs and usage, can often lead to a decline in their experience. Thus, I return to my first phrase message: finding the right balance between complexity and ease of use.

This is why my humble recommendation is to stick to three levels. But I remain open to arguments, especially those related to verified users needs :)

[virgile-dev]

Hey guys,
I stand by what @rl-83 has said.
As a user I sometimes endup using bold for as h4 as use a lot h2 and less h1.
So I'd suggest that has way to cut the apple in half we configure our BlockNote implementation to as deep as h4.
What do you guys say ?