hoangnguyen0403/nextjs-styling

Styling & UI Performance

Priority: P1 (HIGH)

Prioritize Zero-Runtime CSS for Server Components.

Workflow: Set Up Styling

1. Choose library — Tailwind/shadcn (preferred), CSS Modules (scoped), or Ant Design (with client wrappers).
2. Create cn utility — Combine clsx + tailwind-merge for dynamic classes.
3. Configure fonts — Use next/font for zero-CLS self-hosted fonts.
4. Set image dimensions — Always specify width/height or fill on <Image>.

cn Utility Example

See implementation examples

Library Selection

| Library | Verdict | Reason | | :------------------------- | :----------------- | :------------------------------------------------- | | Tailwind / shadcn | Preferred (P1) | Zero-runtime, RSC compatible. Best for App Router. | | CSS Modules / SCSS | Recommended | Scoped, zero-runtime. Good for legacy projects. | | Ant Design | Supported | Use with Client Component wrappers for RSCs. | | MUI / Chakra (Runtime) | Avoid | Forces use client widely. Degrades performance. |

Library Patterns

For specific library setups, see:

• references/scss.md
• references/ant-design.md
• references/tailwind.md (Tailwind/shadcn)

Patterns

1. Dynamic Classes: Use clsx + tailwind-merge (cn utility).

• Reference: Dynamic Classes & Button Example

2. Font Optimization: Use next/font to prevent Cumulative Layout Shift (CLS).

• Reference: Font Setup

3. CLS Prevention: Always specify width/height on images.

Anti-Patterns

• No runtime CSS-in-JS with RSC: MUI/Chakra force 'use client'; prefer Tailwind or CSS Modules.
• No <img> without dimensions: Always set width/height or use fill to prevent CLS.
• No hardcoded conditional classes: Use clsx+tailwind-merge (cn) for dynamic styles.
• No Google Fonts <link> tag: Use next/font for zero-CLS self-hosted fonts.