Native <details name="..."> instead of a checkbox hack — see
patterns/checked-accordion/ for the comparison. Same
name = the browser closes the others automatically, just like
radio buttons.
No checkbox hack, no CSS selector magic needed. The browser handles toggle state, keyboard support, and exclusivity (only one panel open) entirely on its own.
When several panels are allowed open at once (just don't set
name — that's usually enough) or when an open/close
animation beyond the default height jumps is needed, which doesn't run
smoothly without calc-size()/interpolate-size
(Chromium-only, check the build date below again before relying on it).
See the SKILL.md table. Fallback when name isn't
supported: every panel behaves like a normal, independent
<details> — no breakage, just no exclusivity.