There are 2 repositories under zero-runtime topic.
The CSS Language and Framework
🐻❄️ A Headless, Utility-First, and Zero-Runtime UI Component Library ✨
🖌️ Make your <script> lighter and your <style> smarter
Zero-runtime type-safe routing library
Stitches: CSS-in-JS with near-zero runtime + awesome features (tokens, variants, atomic CSS, and more!)
⚡️ Simple CSS in JS on TypeScript with Zero runtime overhead