I would like to split the window in 4 equal parts. In each part I want a picture which is both aligned vertically and horizontally, a bit like [here](http://jsfiddle.net/TFCM4/1/).

The problem is that when I remove one of the pictures, I don't want to other pictures to use that removed picture's space, like [here](http://jsfiddle.net/TFCM4)