next-css-modules v0.1.1

Next.js + CSS

Import .css files in your Next.js project

Installation

npm install --save next-css-modules

or

yarn add next-css-modules

Usage

The stylesheet is compiled to .next/static/css. Next.js will automatically add the css file to the HTML. In production a chunk hash is added so that styles are updated when a new version of the stylesheet is deployed.

Without CSS modules

Create a next.config.js in the root of your project (next to pages/ and package.json)

// next.config.js
const withCSS = require('next-css-modules');
module.exports = withCSS();

Create a CSS file style.css

.example {
    font-size: 50px;
}

Create a page file pages/index.js

import '../style.css';

export default () => <div className="example">Hello World!</div>;

Note: CSS files can not be imported into your _document.js. You can use the _app.js instead or any other page.

With CSS modules

// next.config.js
const withCSS = require('next-css-modules');
module.exports = withCSS();

Create a CSS file style.module.css

.example {
    font-size: 50px;
}

Create a page file pages/index.js

import css from '../style.module.css';

export default () => <div className={css.example}>Hello World!</div>;

With CSS modules and options

You can also pass a list of options to the css-loader by passing an object called cssLoaderOptions.

For instance, to enable locally scoped CSS modules, you can write:

// next.config.js
const withCSS = require('next-css-modules');
module.exports = withCSS({
    cssLoaderOptions: {
        importLoaders: 1,
        localIdentName: '[local]___[hash:base64:5]'
    }
});

Create a CSS file styles.module.css

.example {
    font-size: 50px;
}

Create a page file pages/index.js that imports your stylesheet and uses the hashed class name from the stylesheet

import css from '../styles.module.css';

const Component = props => {
    return <div className={css.example}>...</div>;
};

export default Component;

Your exported HTML will then reflect locally scoped CSS class names.

For a list of supported options, refer to the webpack css-loader README.

PostCSS plugins

Create a next.config.js in your project

// next.config.js
const withCSS = require('next-css-modules');
module.exports = withCSS();

Create a postcss.config.js

module.exports = {
    plugins: {
        // Illustrational
        'postcss-css-variables': {}
    }
};

Create a CSS file style.css the CSS here is using the css-variables postcss plugin.

:root {
    --some-color: red;
}

.example {
    /* red */
    color: var(--some-color);
}

When postcss.config.js is not found postcss-loader will not be added and will not cause overhead.

You can also pass a list of options to the postcss-loader by passing an object called postcssLoaderOptions.

For example, to pass theme env variables to postcss-loader, you can write:

// next.config.js
const withCSS = require('next-css-modules');
module.exports = withCSS({
    postcssLoaderOptions: {
        parser: true,
        config: {
            ctx: {
                theme: JSON.stringify(process.env.REACT_APP_THEME)
            }
        }
    }
});

Configuring Next.js

Optionally you can add your custom Next.js configuration as parameter

// next.config.js
const withCSS = require('next-css-modules');
module.exports = withCSS({
    webpack(config, options) {
        return config;
    }
});