title: Creating a Bartik sub-theme in Drupal 8
body: <p>I have been playing with Drupal 8. At the moment I want to have an image as the header background in Bartik. For this I created a subtheme called "freex" in the following way:</p>
  
  <p>Create folder freex in /themes/custom/</p>
  
  <p>Create freex.info.yml in /themes/custom/freex/ containing:</p>
  
  <pre><code>name: Freex
  description: Basis thema voor verenigingen
  type: theme
  core: 8.x
  base theme: bartik
  
  libraries:
    - freex/global-styling
  </code></pre>
  
  <p>Create file freex.libraries.yml in /themes/custom/freex/ containing:</p>
  
  <pre><code>global-styling:
    version: 1.0
    css:
      theme:
        css/style.css: {}
  </code></pre>
  
  <p>Create file in /themes/custom/freex/css/ called style.css containing:</p>
  
  <pre><code>#header {
  background-color: yellow;
  }
  </code></pre>
  
  <p>Just to see of it works... It doesn't, the header does not change background color. Any ideas as to what I am missing?</p>