At my company, I made the executive decision to drop CSS-in-JS because none of those libraries support PostCSS, and most have their own from-stratch, half-baked

At my company, I made the executive decision to drop CSS-in-JS because none of those libraries support PostCSS, and most have their own from-stratch, half-baked CSS transformation pipeline, not 10% as powerful as the PostCSS ecosystem. I love PostCSS, and I'll happily consider CSS-in-JS again when somebody writes a library that doesn't try to reinvent the wheel.