ng2-dnd how use class css when drag dragOver dropOver for angular2
<p><a href="http://akserg.github.io/ng2-webpack-demo/#/dnd" rel="nofollow noreferrer">http://akserg.github.io/ng2-webpack-demo/#/dnd</a>
this is a demo for this drag&amp;drop using angular2
so how can I affect my class css to indicate that this zone is the droppable zone </p>

<p><a href="https://i.stack.imgur.com/tdgL7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tdgL7.png" alt="enter image description here"></a> </p>

<p>this is a part of code from github source project</p>

<pre><code> _onDragEnterCallback(event: MouseEvent) {
     if (this._dragDropService.isDragged) {
         this._elem.classList.add(this._config.onDragEnterClass);
         this.onDragEnter.emit({dragData: this._dragDropService.dragData, mouseEvent: event});
     }
 }
</code></pre>

<p>how can I affect my class to this line                  <code>this._elem.classList.add(this._config.onDragEnterClass);</code></p>