"Use some of the libraries on the server with NodeJS. i.e. DI." - some, and I'd expect an explicit mentioning of isomorphism if it were possible at the moment to render it on the server side.
Shadow DOM != Virtual DOM. I mean the React-style Virtual DOM.
Virtual DOM is (typically) a pure JavaScript object-based DOM representation that gets somehow flushed to actual DOM (or to WebGL or anything else). You as the programmer use the Virtual DOM directly and try to avoid talking to the real DOM underneath. Virtual DOM has a few advantages, but the one that stands out in today's browsers is limiting DOM thrashing where you query the DOM (requiring an expensive recalc) and then modify the DOM (invalidating what was recalc'd) in a loop.