title: Swiper.js navigation buttons disappear in production mode
body: <p><strong>Swiper.js navigation buttons disappear in production mode</strong></p>
  <p>Swiper.Js navigation button showing in the development but does not show in the production.</p>
  <p><strong>next.config.js</strong></p>
  <pre><code>const withSass = require('@zeit/next-sass');
  const withCSS = require('@zeit/next-css');
  
  module.exports = withCSS(withSass({
    webpack(config) {
      config.module.rules.push({
        test: /\.(png|jpg|gif|svg|eot|ttf|woff|woff2)$/,
        use: {
          loader: 'url-loader',
          options: {
            limit: 100000
          }
        }
      });
  
      return config;
    }
  }));
  </code></pre>
  <p><strong>_app.js</strong></p>
  <pre><code>import 'swiper/swiper.scss';
  import 'swiper/css/swiper.css';
  import 'swiper/components/navigation/navigation.scss';
  import 'swiper/components/pagination/pagination.scss';
  import 'swiper/components/scrollbar/scrollbar.scss';
  import 'swiper/components/effect-cube/effect-cube.scss';
  </code></pre>
  <p><strong>My Component</strong></p>
  <pre><code>SwiperCore.use([Navigation, Scrollbar, A11y]);
  
   &lt;Swiper  
            threshold=&quot;50&quot;
            navigation
            style={{ width: '100%', height: '98%', }}
            scrollbar={{ draggable: true }}
            initialSlide={sliderIndex}    
          &gt;
            &lt;SwiperSlide className={classes.slider}&gt;
              {createPages(0, 8, 0)}
            &lt;/SwiperSlide&gt;
  
            &lt;SwiperSlide className={classes.slider}&gt;
              {createPages(8, 16, 1)}
            &lt;/SwiperSlide&gt;
  
  &lt;/Swiper&gt;
  </code></pre>
  <p>Thanks you for your help</p>