GitHub's Primer team migrated from CSS-in-JS to CSS Modules to address growing performance challenges as component count exploded. The shift eliminates client-side runtime styling costs and SSR performance degradation by rolling styles into native CSS stylesheets sent with the HTML. This change reduces page load times and simplifies style maintenance across the platform.
Background
GitHub's Primer design system powers much of the platform's UI components, making performance optimization critical for user experience at scale.
- Source
- Lobsters
- Published
- Sep 27, 2026 at 03:15 PM
- Score
- 7.0 / 10