ElementInternals/form-associated custom element

[Lichtjaeger]

https://html.spec.whatwg.org/multipage/custom-elements.html#elementinternals
https://html.spec.whatwg.org/multipage/custom-elements.html#custom-elements-face-example

[Schweinepriester]

Available via MDN now: https://caniuse.com/?search=ElementInternals

Not totally sure about formAssociated though.