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CSS Incorporation

Next.js offers several styling options to suit different development needs:

• CSS Modules: Provides locally scoped CSS, helping prevent class name conflicts and making styles easier to manage.
• Global CSS: Straightforward and familiar for those used to traditional CSS, though it can lead to larger CSS files and harder-to-maintain styles in bigger projects.
• Tailwind CSS: A utility-first framework that enables fast, custom UI development through composable utility classes.
• Sass: A widely used CSS preprocessor that enhances CSS with features like variables, nesting, and mixins for better organization.
• CSS-in-JS: Lets you write CSS directly within JavaScript components, offering dynamic, scoped styles tightly coupled with your component logic.

Next.js enhances the styling workflow with features that streamline development and optimize production:

• During local development with next dev, both global styles and CSS Modules benefit from Fast Refresh, allowing style changes to appear instantly as you save.
• In production builds using next build, CSS is automatically minified and bundled into fewer .css files to reduce network requests and improve load times.
• Even if JavaScript is disabled, styles will still load correctly in the production build (next start). However, JavaScript is required during development to enable Fast Refresh.

Next.js optimizes CSS in production by automatically chunking and merging stylesheets. The final CSS order is based on the sequence in which styles are imported in your code.

To ensure consistent and predictable styling, follow these best practices:

• Import each CSS file in only one JS/TS file. For global styles, import them in the desired order within a single file to maintain consistency.
• Favor CSS Modules over global styles. Use a clear and consistent naming pattern like ComponentName.module.css to keep styles modular and manageable.
• Move shared styles into reusable components. This promotes reuse and reduces redundancy.
• If you're using Tailwind CSS, import it at the very top of your Root Layout file to ensure it loads first.
• Disable linters or formatters (e.g., ESLint's sort-imports) that auto-sort imports, as the import order directly impacts how CSS is applied.