title: Nextjs external css not updating on client side page transitions
body: <p>I am still new to nextjs so i don't know if this is a bug or if i just wrongly implemented it. </p>
  
  <p>I successfully managed to extract all my scss files using this guide:
  <a href="https://github.com/zeit/next-plugins/tree/master/packages/next-sass" rel="nofollow noreferrer">https://github.com/zeit/next-plugins/tree/master/packages/next-sass</a></p>
  
  <p>Everything works just fine while using server side rendering. External css file gets properly updated and applied, but as soon as i do client side page transitions the new scss import doesnt get injected in the external css file. I also dont want to prefetch every scss file on the initial pageload it should dynamically fetch and update the external file on server side routing and client side routing.</p>
  
  <p>My next.config.js </p>
  
  <pre><code>const getRoutes = require('./routes');
  const path = require('path');
  const withSass = require('@zeit/next-sass');
  
  module.exports = withSass({
    exportPathMap: getRoutes,
    // useFileSystemPublicRoutes: false,
    cssModules: true,
    cssLoaderOptions: {
      importLoaders: 1,
      localIdentName: "[local]___[hash:base64:5]",
    },
  })
  </code></pre>
  
  <p>Example Component</p>
  
  <pre><code>import { Fragment } from 'react';
  import Main from '../components/main';
  import style from '../styles/pages/parkett.scss';
  
  const Parkett = () =&gt; 
    &lt;Fragment&gt;
      &lt;section className={`section ${style.sec_two_parkett}`}&gt;
        &lt;div className={`sec_text ${style.sec_two_text}`}&gt;
          &lt;h2 className="didonesque_headline"&gt;Detailiert&lt;/h2&gt;
          &lt;p className="normal_text"&gt;Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.&lt;/p&gt;
        &lt;/div&gt;
      &lt;/section&gt;
      &lt;section className={`section ${style.sec_three_parkett}`}&gt;
        &lt;div className={`sec_text ${style.sec_three_text}`}&gt;
          &lt;h2 className="didonesque_headline"&gt;Erstaunlich&lt;/h2&gt;
          &lt;p className="normal_text"&gt;Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat.&lt;/p&gt;
        &lt;/div&gt;
      &lt;/section&gt;
    &lt;/Fragment&gt; 
  
  export default () =&gt; 
    &lt;Main 
      title="parkett" 
      component={&lt;Parkett /&gt;} 
      links={['Treppe', 'Moebel', 'Innenausbau']}
      /&gt;
  </code></pre>