UX: Improve style of GitHub PR body in emails (PR #13198)

On web, we display only an excerpt in a monospace font and the email did not use the same style.

GitHub

Do we need the !important there? It should only be used as a last case resort.

Can we trim the excerpt instead of hiding it?

In correct_first_body_margin from below, margin-top:0 is set for all <p> elements. I could not target the parent element either, so I had to use !important.

I think you can call remove (or delete) directly

      @fragment.css('.github-body-container .excerpt').remove

Nice.

Maybe add a test as well to ensure we don’t regress?