I think it’s kinda cool to see Google dropping repos of interesting web components. It demonstrates the possibilities of cool new web features and allows them to ship them in a way that’s compatible with entirely web standards.
I wanted to give it a try, so I linked up their example
two-up-min.js script in a Pen and used the element by itself to see how it works. They expose the component’s styling with custom properties, which I’d say is a darn nice use case for those.