Weird spacing after `\begin{proof}` in certain cases

[diomidov]

What's wrong?

If a proof immediately follows a lemma (or similar) that ends in a list with no blank line between \end{lemma} and \begin{proof}, then the spacing between the first two paragraphs of the proof is reduced.

• If there is a blank line between the lemma and the proof, everything looks fine
• If the second environment is another lemma, everything looks fine
• If the lemma ends in a normal paragraph, everything looks fine
• If the list is not in a lemma, the proof starts inside the list (which is weird, but consistent with markdown spec)
• If the list is in a markdown blockquote (>) instead of a lemma, the proof starts inside the list inside the blockquote (which is also consistent with markdown spec)

How to Reproduce

Steps to reproduce the behavior, e.g., link to where to see the behavior:

1. Go to https://coauthor.csail.mit.edu/coauthor-dev/m/YTPDxhxvBKkH4jiTo

Context

• Device/OS: Linux
• Browser: Firefox
• Coauthor server: CSAIL

[diomidov]

Relatedly, I think the proofs should be wrapped in a <div class='proof'>, similarly to how the other environments are wrapped in a <blockquote class='thm'>.