UI Kernel: Design Tokens as Symfony infrastructure

For years, Symfony teams solved UI scaling one of two ways.

Either you adopted a JavaScript build pipeline — Webpack Encore, Vite, npm scripts — and a utility CSS framework like Tailwind.

Or you stayed "PHP-first" and watched every project grow its own app.css, its own spacing scale, its own dark-mode hacks, and its own Bootstrap overrides.

Both paths work. Neither scales cleanly across agencies, products, and long-lived admin UIs.

UI Kernel is Symfinity's answer on the Symfony side: treat design tokens as infrastructure — resolved in PHP, emitted as CSS custom properties, consumed by Twig and component CSS — without making Node the gatekeeper of your theme.