Missed cover behaviour

[enbeltran87]

Exactly what css property do: background-size: cover;
When the size of the slider has a different proportion than images we get a blank space over and down of the image, if the proportion difference is in height, image height proportion < image container proportion. Ej: container: 16:9 , image: 16:6.
I review the code and i find the problem, the width of the image is allways the 100% of the container and then manage the top margin to keep it in middle. But the correct behaviour is if the height of the image is less than container, then make equal the height and handle the overflow of the width.