React not rendering css styles

I am trying to add a dropdown menu to my application and I picked Selectize (https://github.com/furqanZafar/react-selectize). But it appears that it is not displayed correctly on the page. This is what is looks like, it seems that the css styles are missing. I am quite a rookie to React so please bear with me if this is not a smart question. Thanks in advance!

webpack.config.js

var path = require("path")
var webpack = require('webpack')
var BundleTracker = require('webpack-bundle-tracker')

module.exports = {
  context: __dirname,

  entry: './assets/js/index', 

  output: {
      path: path.resolve('./assets/bundles/'),
      filename: "[name]-[hash].js",
  },

  plugins: [
    new BundleTracker({filename: './webpack-stats.json'}),
  ],

  module: {
    loaders: [
      {test: /\.jsx?$/, exclude: /node_modules/, loader: 'babel-loader', query: { presets:['react'] }}, 
      {test: /\.css$/, loader: 'style-loader'},
      {test: /\.css$/, loader: 'css-loader', query: { modules: true, localIdentName: '[name]__[local]'}},
    ],
  },

  resolve: {
    modulesDirectories: ['node_modules', 'bower_components'],
    extensions: ['', '.js', '.jsx']
  },
}

Dropdown.js

import {ReactSelectize, SimpleSelect, MultiSelect} from 'react-selectize';
import React from 'react';
import 'react-selectize/themes/index.css'


export default class Dropdown extends React.Component {
    render() {
        return (
            <SimpleSelect placeholder="Select a fruit" onValueChange={value => alert(value)}>
                <option value = "apple">apple</option>
                <option value = "mango">mango</option>
                <option value = "orange">orange</option>
                <option value = "banana">banana</option>
            </SimpleSelect>
        )
    }
}

index.js

import Dropdown from "./components/dropdown"

var React = require('react')
var ReactDOM = require('react-dom')

ReactDOM.render(<Dropdown />, document.getElementById('container'))

The following error was in the console:

Uncaught Error: addComponentAsRefTo(...): Only a ReactOwner can have 
refs. You might be adding a ref to a component that was not created 
inside a component's `render` method, or you have multiple copies of 
React loaded