How can I make the image fill the whole container?

I want to make the image always fill width and height.

I am using LayerSlider WP plugin so I set width 100% at its settings and also width: 100% !important into a field that says "custom css"

PS: This is the link http://ift.tt/1pFyMiD (you will see I added a very small and squared image in the first slide and a wider image for the second one but still doesnt fill the full width)

Thanks !

via Chebli Mohamed