Firefox for Web DevelopersHTML might be getting a new type of tag, which… hasn't happened this millennium. Here's the new syntax, and how it works.
And here's the explainer on HTML patching https://github.com/WICG/declarative-partial-updates/blob/main/patching-explainer.md
Ténno Seremél’@firefoxwebdevs Eh… Unsure who the users of this feature are. At the very least I’m pretty sure I’ll never need it.