STYLEX: A STYLING LIBRARY FOR CSS AT SCALE

Summary from the TLDR Dev newsletter

StyleX is Meta's default, open-source styling system. Designed for large-scale applications, it combines the ease of CSS-in-JS with the performance of static CSS generation. StyleX compiles styles at build time into atomic CSS. It enforces constraints to avoid conflict-prone patterns, like styling at a distance, to guarantee style encapsulation.