The spec appropriately points out that this is a fragile technique. Also to avoid any doubt: if something’s called a golfing trick, you almost certainly should

The spec appropriately points out that this is a fragile technique. Also to avoid any doubt: if something’s called a golfing trick, you almost certainly shouldn’t use it on normal code. I confess I use this technique on every page on my website, in my carefully-golfed light/dark mode switcher. (https://chrismorgan.info/blog/dark-theme-implementation/ https://chrismorgan.info/blog/dark-theme-implementation/ has a slightly-expanded version of it, and uses a more sensible document.querySelector instead.)