My favorite technique for filling up a parent container 100% width and height is to use absolute positioning:
parent {
position: relative; /* unless it's already positioned */
}
child {
position: absolute;
top: 0;
bottom: 0;
left: 0;
right: 0;
}
Here it is applied to your JSFiddle: http://jsfiddle.net/Kgz5p/