title: Unable to edit 'URL'. The style sheet must be part of the project
body: <p>I have been getting this error in Visual Studio 2012 every time I try type an element and the class attribute (i.e. <code>&lt;div class="</code>). It will popup and some times it even crashes Visual Studio if I hit enter too fast.</p>
  
  <p><img src="https://i.stack.imgur.com/93TB5.png" alt="enter image description here"></p>
  
  <p>Is there anyway to get rid of this error while still getting the list of all the CSS classes? </p>