-webkit-overflow-scrolling : touch in jQuery Mobile panels under iOS 5

Question

I know this problem has already been discussed, but I'm not here for the scroll in jQM panels. The solution given here works perfectly : Scroll JQuery Mobile Panel Separately From Content

.ui-panel.ui-panel-open {
    position:fixed;
}
.ui-panel-inner {
    position: absolute;
    top: 1px;
    left: 0;
    right: 0;
    bottom: 0px;
    overflow: scroll;
    -webkit-overflow-scrolling: touch;
}

At least under iOS 6 and 7. Under iOS 5, it doesn't work at all. I can scroll the content of the page, but the panel stays fixed when I open it. I tested the -webkit-overflow-scrolling : touch property, and it works in other websites. I just need it working with jQuery Mobile.

The website would be perfect if you could help me to make this work!

Thank you all in advance, Adrien B.