-webkit-overflow-scrolling: touch in iOS and spurious scroll from someone else's block?

Question

css

Hello.
Sandbox on the issue:
cssdeck.com/labs/49cru2n9
There is a main long block with overflow and a footer with abs positioning.
The problem is on iOS. When scrolling on the footer (in the example it is gray), nothing happens. As soon as we add this block to the main block for the finger, it seems to become transparent and the main block scrolls through it. How is such an event possible? Moreover, html and body
-webkit-overflow-scrolling: touch

position: fixed;
overflow: hidden;