First you need to setup webpack to load your css files using "css" loader and enable CSS modules. You will also need to use extract-text-webpack-plugin to aggregate the CSS into a single file. Refer to webpack-demo.

Then you need use the higher order component declaration pattern to "decorate" your component, e.g.

import React from 'react';
import styles from './car.css';
import CSSModules from 'react-css-modules';

class Car extends React.Component {
    render () {
        return <div className='car'>
            <div className='front-door'></div>
            <div className='back-door'></div>
        </div>;
    }
}

export default CSSModules(Car, styles);

Thats it!

CSSModules extends Car render method. It will look for CSS classes in ./car.css that match ReactElement className and will append the matching unique class names to className declaration.