Tailwind CSS vs. CSS-in-JS: The Final Verdict

For years, we fought over "Separation of Concerns". Then Tailwind came along and said: "Put your styles in your HTML."

The Case for Tailwind

1. Colocation: You see the structure and style in one place.
2. No Context Switching: No jumping between .js and .css files.
3. Performance: Tailwind generates a tiny static CSS file. CSS-in-JS adds runtime overhead (calculating styles on the browser).
4. Standardization: Every developer knows what p-4 means. WrapperDiv could mean anything.

The Case for CSS-in-JS (Styled Components)

1. Dynamic Styles: Changing color based on props is easier.
2. Isolation: Zero chance of class name collision (though Tailwind fixes this too).

The Server Component Factor (Next.js App Router)

RSC (React Server Components) requires zero runtime JS.

• Tailwind: Works perfectly (Static CSS).
• Emotion/Styled-Components: Struggle with RSC (require 'use client' wrapper).

Conclusion

In the era of Next.js and RSC, Tailwind CSS is the clear winner. The runtime cost of CSS-in-JS is too high.