Jeong Min Oh

CSS-in-JS made styling React components feel natural, but it came with a cost: style work at runtime, and libraries that rely on a Provider and context do not fit easily into React Server Components. Many zero-runtime alternatives remove that cost by changing how you write styles, with separate style files or static-only values.Devup UI takes another path. You keep conditionals, dynamic values, responsive arrays and pseudo-selectors in your JSX, and a Rust extractor compiles them into plain class names and CSS variables at build time. In this talk, I will open up that extractor, show what happens to each pattern, and share the trade-offs we found while bringing it to Next.js, Vite, Rsbuild and Webpack.