@raphaelbastide The CSS is being interpreted, it's just that there may be existing styles which are more specific than your own (definitely the case for h1).
We don't actively recommend that people use the preview for writing HTML intended to be used in other contexts, but we do occasionally use it ourselves so it's not really a bug.
In the short term you can use !important on your rules. In the long term we might work on a different rendering method to support your use case.
@cryptpad Ok that make sense. Do you plan to make or support a CSS / JS / HTML collaborative pad like glitch.com? I think such a thing really misses in the open source / self hosted world.
@raphaelbastide It's not currently on our roadmap. The only new apps we have planned are forms (like gforms, surveymonkey, etc.) and a basic calendar (initially for the purpose of setting and viewing reminders about form submission deadlines). We've already secured an R&D grant for these projects.
Anything more is going to depend on either open-source contributions or a drastic change in our funding.
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!