title: Adding already defined CSS into another CSS
body: <p>The title is a bit confusing, so let me show you. Lets say I have the following inside CSS file:</p>
  
  <pre><code>#container_1 {
      width:50%;
      border:1px solid black;
      }
  
  #container_2 {
      background-color:red;
      padding:5px;
  }
  </code></pre>
  
  <p>If I want the container_2 to have 50% width and 1x border, same as the container_1, is there some way to define CSS of container_2 while including the CSS from container_1 without actually having to put in 50% width and 1x border for CSS of container_2?</p>
  
  <p>Something like:</p>
  
  <pre><code>#container_2 {
      include:#container_1;
      background-color:red;
      padding:5px;
  }
  </code></pre>
  
  <p>Thanks</p>