)
}
```
> **Good to know:** If you need broader browser support for very old browsers, see the [Tailwind CSS v3 setup instructions](/docs/app/guides/tailwind-v3-css).
## CSS Modules
CSS Modules locally scope CSS by generating unique class names. This allows you to use the same class in different files without worrying about naming collisions.
To start using CSS Modules, create a new file with the extension `.module.css` and import it into any component inside the `pages` directory:
```css filename="/styles/blog.module.css"
.blog {
padding: 24px;
}
```
```tsx filename="pages/blog/index.tsx" switcher
import styles from './blog.module.css'
export default function Page() {
return
}
```
```jsx filename="pages/blog/index.js" switcher
import styles from './blog.module.css'
export default function Page() {
return
}
```
## Global CSS
You can use global CSS to apply styles across your application.
Import the stylesheet in the `pages/_app.js` file to apply the styles to **every route** in your application:
```tsx filename="pages/_app.js"
import '@/styles/global.css'
export default function MyApp({ Component, pageProps }) {
return
}
```
Due to the global nature of stylesheets, and to avoid conflicts, you should import them inside [`pages/_app.js`](/docs/pages/building-your-application/routing/custom-app).
## External stylesheets
Next.js allows you to import CSS files from a JavaScript file. This is possible because Next.js extends the concept of [`import`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/import) beyond JavaScript.
### Import styles from `node_modules`
Since Next.js **9.5.4**, importing a CSS file from `node_modules` is permitted anywhere in your application.
For global stylesheets, like `bootstrap` or `nprogress`, you should import the file inside `pages/_app.js`. For example:
```jsx filename="pages/_app.js"
import 'bootstrap/dist/css/bootstrap.css'
export default function MyApp({ Component, pageProps }) {
return
}
```
To import CSS required by a third-party component, you can do so in your component. For example:
```jsx filename="components/example-dialog.js"
import { useState } from 'react'
import { Dialog } from '@reach/dialog'
import VisuallyHidden from '@reach/visually-hidden'
import '@reach/dialog/styles.css'
function ExampleDialog(props) {
const [showDialog, setShowDialog] = useState(false)
const open = () => setShowDialog(true)
const close = () => setShowDialog(false)
return (
)
}
```
## Ordering and Merging
Next.js optimizes CSS during production builds by automatically chunking (merging) stylesheets. The **order of your CSS** depends on the **order you import styles in your code**.
For example, `base-button.module.css` will be ordered before `page.module.css` since `` is imported before `page.module.css`:
```tsx filename="page.tsx" switcher
import { BaseButton } from './base-button'
import styles from './page.module.css'
export default function Page() {
return
}
```
```jsx filename="page.js" switcher
import { BaseButton } from './base-button'
import styles from './page.module.css'
export default function Page() {
return
}
```
```tsx filename="base-button.tsx" switcher
import styles from './base-button.module.css'
export function BaseButton() {
return
}
```
```jsx filename="base-button.js" switcher
import styles from './base-button.module.css'
export function BaseButton() {
return
}
```
### Recommendations
To keep CSS ordering predictable:
* Try to contain CSS imports to a single JavaScript or TypeScript entry file
* Import global styles and Tailwind stylesheets in the root of your application.
* **Use Tailwind CSS** for most styling needs as it covers common design patterns with utility classes.
* Use CSS Modules for component-specific styles when Tailwind utilities aren't sufficient.
* Use a consistent naming convention for your CSS modules. For example, using `.module.css` over `.tsx`.
* Extract shared styles into shared components to avoid duplicate imports.
* Turn off linters or formatters that auto-sort imports like ESLint’s [`sort-imports`](https://eslint.org/docs/latest/rules/sort-imports).
* You can use the [`cssChunking`](/docs/app/api-reference/config/next-config-js/cssChunking) option in `next.config.js` to control how CSS is chunked.
## Development vs Production
* In development (`next dev`), CSS updates apply instantly with [Fast Refresh](/docs/architecture/fast-refresh).
* In production (`next build`), all CSS files are automatically concatenated into **many minified and code-split** `.css` files, ensuring the minimal amount of CSS is loaded for a route.
* CSS still loads with JavaScript disabled in production, but JavaScript is required in development for Fast Refresh.
* CSS ordering can behave differently in development, always ensure to check the build (`next build`) to verify the final CSS order.
## Next Steps
Learn more about the features mentioned in this page.
- [Tailwind CSS](/docs/pages/guides/tailwind-v3-css)
- Style your Next.js Application using Tailwind CSS.
- [Sass](/docs/pages/guides/sass)
- Learn how to use Sass in your Next.js application.
- [CSS-in-JS](/docs/pages/guides/css-in-js)
- Use CSS-in-JS libraries with Next.js
---
For a semantic overview of all documentation, see [/docs/sitemap.md](/docs/sitemap.md)
For an index of all available documentation, see [/docs/llms.txt](/docs/llms.txt)