A slight regression in the new non-<details>-based collapsible sections: if you click a link to a tree in the TOC which has a collapsed ancestor, that ancestor doesn't get uncollapsed so it looks to the user like the link went nowhere.
For an example, try clicking some of the TOC links in this page: https://www.jonmsterling.com/019X/
https://tangled.org/jonmsterling.com/ocaml-forester/commit/b3970627de813f7b4079ea10d515c4aa8a603871