import "./FileName.css"; // import your css file

​

// or css inside your react file

//for example:

const MyDiv = React.createClass({

  render: function() {

    const style = {

      color: 'white',

      fontSize: 200

    };

    return <div style={style}> Have a good and productive day! </div>;

  }

});

import React, { Component } from 'react';

import './Button.css'; // Tell webpack that Button.js uses these styles

​

class Button extends Component {

  render() {

    // You can use them as regular CSS styles

    return <div className="Button" />;

  }

}

.Button {

  padding: 20px;

}