Dimitri: Okay, I can follow up with Ryosuke. I’m happy to share our thoughts and needs for subclassing components.
Anne/Steve: I’d originally indicated that this technique couldn't be applied to extending native HTML elements. Since the two of your seemed interested in that, I spent some time tinkering with the idea, and it turns out that this technique can be made to work for that situation. I’ve posted a quick demo (http://janmiksovsky.github.io/base-template/extendButton.html <http://janmiksovsky.github.io/base-template/extendButton.html>) showing subclassing of a standard HTML button element. This works best under native Shadow DOM. Under polyfilled Shadow DOM, base class styles can’t (yet?) be inherited. Anyway, I mention this in case it opens up some ideas. Thanks for the inspiration!