Close but not exactly, there is no esoteric HTC stuff for example.

   element.selector {
     prototype: ClassName url(in-module.js);
     color: blue;
     ...
   }

That above is significantly better than almost-dead-at-birth WebComponents:

   let customElementRegistry = window.customElements;
   customElementRegistry.define('my-custom-element', MyCustomElement);

One simple CSS property instead of 20+ additional entities https://developer.mozilla.org/en-US/docs/Web/Web_Components

Used quite a lot actually, on half of machines where Sciter is installed (~500..600 mln machines :)

Web Components is a marketing coup. It’s a great name. People wish it existed and did the thing it says. So they ignore that customElement and shadow DOM are two terrible APIs that are best ignored by 99% of developers…

Meanwhile, shit that would actually help framework authors, like native morphDOM don’t happen.