Ah yes that's what I was wondering. So Custom Elements are actually part of the Web Components standard, and it looks like it was already implemented in Chrome

Ah yes that's what I was wondering. So Custom Elements are actually part of the Web Components standard, and it looks like it was already implemented in Chrome and Opera, works with a flag under Firefox and so now it has landed in Webkit / Safari, right? Besides Edge, and safari's support for HTML imports, it looks like Web Components implementation is slowly getting there. What about uses? Are there any popular webcomponents out there yet?