title: How to replace a CSS class by another one when i change the media
body: <p>I'm new in the usage of CSS, and i'm still in the learning curve</p>
  
  <p>Basically, i want to display a section using the class col-xs-12 when i select the media <code>print</code> instead of a col-xs-9 in all other medias.</p>
  
  <p>Is there an easy way in CSS to do that ?</p>