Thankfully Firefox recently changed their stance from "Neutral" to "Positive". https://github.com/mozilla/standards-positions/pull/740 https://github.com/mozil

Thankfully Firefox recently changed their stance from "Neutral" to "Positive". https://github.com/mozilla/standards-positions/pull/740 https://github.com/mozilla/standards-positions/pull/740 > Neutral stance: We're not convinced that the complexity this feature introduces upon the HTML parser carries its weight in terms of usefulness for web developers. There's also a risk that the processing model is not compatible with a future declarative custom elements feature as it was developed in isolation. Having said that, the proposal is a reasonable approach for this functionality that takes into account the various constraints and security considerations that come with changing the HTML parser. > Positive Stance: This is a reasonable proposal which takes into account the various constraints and security considerations that come with changing the HTML parser. Hopefully that's a sign of things to come! (Fingers crossed)