I'd like to add definitions, theorem, lemmata and their corresponding proofs in a fashion similar to that of Latex. These are not necessarily only math mode content and their interior should be subject to all other transformations done from Markdown, e.g. lists, quotes, tables...

One prototype for syntax is to allow configuration items on quotes as quotes allow nesting of other markdown blocks. The extra nesting at the start of a paragraph is not quite optimal for long proofs but other options are much worse.

• Code fences do not parse and allow any inner elements.
• Headings do not have any explicit end markers, see previous attempts with beamer.
• Tables, includes, and links do not add anything obvious to the table
• Lists also have nesting but the semantics seem weird and it is not obvious how multiple items should be interpreted. Other than that they are the same as quotes.

Ideally, this would work and lazy paragraph continuation could remove some quote indentation.

{theorem, caption="The main theorem"}
> There is an infinite number of prime numbers.

{proof}
> Assume `$ p` to be the largest prime number. Define
> ```$$
P' = 1+ \prod^p_{i=0, i prime} i
```
> Then `$ P'` is not divisible by any prime. But it has at least two divisors, one and itself, so there must a prime divisor larger than `$ p`. This is a contradiction.