Scroll Bar in Openlayers 3 popup

Question

In this example of OPenlayers 3 : http://jsfiddle.net/api/post/library/pure/ , I was trying to make the ol3 popup scrollable whenever the content in it is very large. I set the following style for popup content div :- <div id="popup-content" style="max-height:300px;overflow:auto;"> This inserts scroll bar if content is greater than 300 px but disables mouse events like zoom,hover,click etc. Could anyone tell why is this happening and what is the right way to add scroll in popup?