How to fit the image size inside Leaflet popups?

Question

I'm doing an experiment with gifshot and leafletjs. I want to insert an image inside a marker popup but the problem is that the popup will not adapt his size to fit the content. I've tried to apply some css rules but it will not be displayed on the marker that is present on the map, I need some tips and help to fix this. Here is an image that is showing my problem:

var animatedImage;

map.on('click', function(event){
 marker = map.mouseEventToLatLng(event.originalEvent);
 var icns = L.marker([marker.lat, marker.lng]).addTo(map);
 sessionStorage.setItem('lat', marker.lat);
 sessionStorage.setItem('lng', marker.lng);
 gifshot.createGIF({}, function(obj){
    if(!obj.error) {
      var image = obj.image,
      animatedImage = document.createElement('img');
      animatedImage.src = image;
      icns.bindPopup(animatedImage).openPopup();
    }       
  });
});

Any help will be appreciated.