CSS error with position and overflow on all browsers

Question

I have set up a scrollable div that until recently was scrolling and now appears to be jammed at the top. The only difference is the addition of position: relative;.

Here is a FIDDLE

http://jsfiddle.net/PMzcB/

Any ideas why?

Answer 1

The z-index:-1; was the problem.

http://jsfiddle.net/PMzcB/13/

Answer 2

Change z-index to a positive value.