CSS-in-JS: The Great Betrayal of Front End Sanity

Summary

We were promised elegance. What we got was runtime CSS parsing, unreadable class names, and hydration bugs straight out of hell. CSS-in-JS was supposed to free us from global namespace nightmares and styling spaghetti. Instead, it wrapped us in a shiny new layer of chaos — one that performs worse, reads worse, and somehow costs more CPU cycles to do what a plain stylesheet did perfectly fine two decades ago. This is not evolution; I’d call it over-engineering disguised as progress. From Liberation to Performance Lock-In When CSS-in-JS first appeared, it felt revolutionary. No more global leaks, no more worrying about specificity wars, no more cryptic class collisions. We could co-locate styles with components, making everything modular and “self-contained.” But the honeymoon ended quickly. Quickly, developers realized that generating styles at runtime wasn’t a small tradeoff — it was a ticking performance bomb. What started as a way to simplify styling turned into one of the most expensive abstractions ever introduced into frontend development. By tying CSS generation to JavaScript execution, we effectively welded presentation to logic — the exact thing we were trying to avoid when we invented CSS in the first place. The idea of dynamically computing CSS on the client side sounds clever, until you’re debugging a hydration mismatch at 3 a.m. because some SSR pass decided to hash class names differently between the server and browser. It’s the kind of issue that feels less like a bug and more like a punishment for trusting marketing copy. CSS-in-JS libraries made the simple act of styling a button as complex as dependency injection. And let’s not even start on how much bundle size ballooned just to make borders blue. By tying CSS generation to JavaScript execution, we effectively welded presentation to logic — the exact thing we were trying to avoid when we invented CSS in the first place. The elegance of separation was replaced with inline chaos wrapped in hooks and ...