Background-Position

The cat, Astrophy, should be sitting at the bottom right hand corner whatever the size of the window.

Here is a screenshot of the correct behaviour: Astrophy should be sitting at the bottom right of the
viewport. Note how Astrophy is not cut by the bottom or right viewport edges.

This is what happens when background-attachement is set to scroll, but when set to fixed, the background-position property no longer affects the starting position on the canvas, only the starting position of the image itself.