title: Webpack postcss prefixer in vue-cli 3
body: <p>I need to prefix the Bulma css classes by using webpack. I found an example but my app uses Vue CLI 3 and I'm not sure how to translate the webpack config to a vue.config.js.</p>
  
  <p><a href="https://github.com/uu1t-sandbox/example--webpack-config-prefixed-bulma/blob/master/webpack.config.js" rel="nofollow noreferrer">This is the webpack config</a></p>
  
  <p>In my <code>vue.config.js</code> I have the following:</p>
  
  <pre><code>  chainWebpack: config =&gt; {
      config.module
        .rule('css-prefixer')
        .use(['style-loader', 'css-loader'])
        .loader('postcss-loader')
        .tap(options =&gt; {
          // Prefixer goes here
          return options
        })
    }
  </code></pre>
  
  <p>Which gives some internal webpack errors.</p>