I can tell that a lot of hard work went into this, which I really appreciate and admire. But I think this approach is fundamentally flawed because it attempts to solve one problem (managing CSS) by replacing it with an entirely novel problem (new syntax and interface for managing styles).

I would rather see tools that attempt to solve hyperspecific probems (e.g. culling unused styles, visualizing namespace collisions) without disturbing existing best practices (e.g. modular CSS, BEM, using preprocessors like SCSS and post-processors like PostCSS).