Render custom elements in light and shadow dom

Now with slots!

(blank custom element with placeholder info in slots)

(complex example with slot A placeholder inside a web component that users can fill with their own markup, with the effect of composing different DOM trees together.
name
The name of the slot.
default slot)
template (light) A mechanism for holding client- side content that is not to be rendered when a page is loaded but may subsequently be instantiated during runtime using JavaScript. Note: the style element is only injected once since it's global.
light
(no value) renders to light dom
(default slot in shadow) template (shadow) A mechanism for holding client- side content that is not to be rendered when a page is loaded but may subsequently be instantiated during runtime using JavaScript. Note: the style element is cloned with the template.

(put a dynamic instance here)

See MDN for the original version of this demo.