title: How do I trun off the menu .main-navigation using media equries
body: <p>I am using the wordpress  <a href="https://wordpress.org/themes/twentytwelve/" rel="nofollow">twenty twelve theme</a></p>
  
  <p>I am unable to turn off the menu at 800 px, using media queries.</p>
  
  <p><a href="http://hallmusicstudio.phinhall.net/" rel="nofollow">my site</a> </p>