In reply to cbirdsong.

Just want to echo what @cbirdsong says here: This proposal is for the absolute possible light weight system that can provide theme values to Core and 3rd parties without dictating how people choose to build their front ends. It's more than just design tokens, but it would not provide sufficient CSS/tools to build a totally custom theme.

Building consensus around a proposal like this is difficult, so it should seek to be as minimal as possible but sufficient to enable us to make content more portable between themes and more interoperable with plugins and themes.