I noticed that part of this answer is not rendered.
It looks like
whereas the text box and the preview clearly show the full content:
~~ snip ~~
What is going on here?
Known issue with old posts - the renderer at the time had a bug and partial HTML was cached in the answer table for it.
Any edit to the answer will sort it (and has - I just opened for edit and saved).
Other threads on meta with the same issue (I am sure there are more):