How to make centre cropped image responsive?

Question

Based on an existing answer, I have managed to centre crop an image. I am having trouble making the centre cropped image responsive, though.

Question

Answer 1

Does adding this (fiddle) to .center-cropped-img achieve what you want? or do you not want to change the area that is being cropped?

    max-width: 640px;
    width: 100%;