title: Does Bootstrap 3 really use @screen-md-min in its own Less files?
body: <p>On this page <a href="http://getbootstrap.com/css/" rel="nofollow">http://getbootstrap.com/css/</a>, it appears that Bootstrap 3 uses variables such as <code>@screen-md-min</code>. </p>
  
  <p>However, I downloaded its source files, searched all its Less files, and am unable to find it. </p>
  
  <p>Did I miss something? In which Less file does @screen-md-min appear?</p>