Theorem subfiles leave an empty slide when a slide break follows the include #457

Theorem subfiles such as _subfiles/proof-writing/_thm-proof-by-contradiction.qmd put {{< slidebreak >}} before the ::: {.content-hidden when-format="revealjs"} div that holds the proof. On slides the proof is removed, but the break stays. When the including page puts its own {{< slidebreak >}} after the include, as the lab's chapters do between units, the two breaks sit back to back and the deck gets an empty slide.

Morrison-Lab/mcs found this in its own theorem subfiles: eight empty slides in one deck. mcs#7 fixed it by moving the break inside the hidden div, before ::: proof. That keeps the break in HTML and PDF, where it does nothing anyway, and drops it with the proof on slides.

The same fix would apply to every _thm-*.qmd subfile here with that pattern. First confirm by counting empty <section>s in a deck that includes one of them.

Posted by Claude Code (AI agent) --- not written by a human.