e (ngClass)</h2>
      <button ng-click="dn_fade=!dn_fade">Toggle Class</button>
      <div class="element" ng-class="{'dn-fade':dn_fade}">
        ...
      </div>

      <h2>.dn-fade (ngShow)</h2>
      <button ng-click="dn_fade_ngShow=!dn_fade_ngShow">Toggle Show / Hide</button>
      <div class="element dn-fade" ng-show="dn_fade_ngShow">
        ...
      </div>
    </section>

    <section>
      <h2>.dn-fade-up</h2>
      <button ng-click="dn_fade_up=!dn_fade_up">Toggle Class</button>
      <div class