I checked yout code in firefox 3.6 on OS X and this works for me. To get it working, I added:
html, body { height:100%; }
http://jsfiddle.net/XcdJ3/
However, if you have an iframe in any container, it should also have a height:100% property.
Like in this example:
http://jsfiddle.net/XcdJ3/2/
If you cannot deploy the iframe using html and css, try doing this in JavaScript, just take the height of the parent element and apply it to the iframe height tag.
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