title: How can I add / remove classes to an element via AngularJS that's out of $scope?
body: <p>I have a DOM element called <code>.nav-bar</code>. I want to add a class to it from another Angular controller that has it's own <code>$scope</code>. Is such a thing possible?</p>
  
  <p>I have a navigation bar that needs to be loaded one of several controllers. Depending on which controller / view loads it, it has to have a class conditionally applied.</p>