And it fixes a few other unexpected problems as well.
We use SHA1 hashes of the CSS classes' contents as it's name when using CSS modules. This has the cool side effect of making any 2 classes that do the same thing to have the same name, and get de-duped in the final output, regardless of where they originated in the application.
When I saw it happen the first time, it really kind of cemented in the idea that this combined with a way to "punch through" the modularity to combine and extend "base" classes and include global colors (for us it's SASS imports) has pretty much "solved" CSS for me.