Superfish vertical dropdown menu z-index problem in ie7

I found many questions about this issue and i tried all of the solution i found (z-index to parent, relative position to parent, the corner plugin etc...), but nothing seems to help. Here is the demo:

http://visztpeter.me/Develop/index.html

Works in all browser, except IE7. Any idea?

Ok, i found a solution:

aside nav li{
z-index:1;
}

aside nav li.sfHover {
z-index:2;
}

So basicly i just need to add more z-index to the list element that has dropdown menu inside.