Problem:
--------

On iOS the `z-index` of a scrollable area is ignored when using `-webkit-overflow-scrolling`. If two objects with `-webkit-overflow-scrolling` overlap the lower one is scrolled instead of the one being displayed above.

How to reproduce:
-----------------

Create two elements overlaying each other (with `position: absolute` for example), one of them having a higher `z-index` and add

```
.selector
{
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}

```

to both of them. Both elements should have enough content to be scrollable.

Additionally add 

```
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="apple-mobile-web-app-capable" content="yes"> 
<meta name="apple-mobile-web-app-status-bar-style" content="black">

```

to your `<head>`. Then add the page to your home screen and launch it from there.

If you then try to scroll the upper element the element beneath is scrolled instead.

### MCVE:

Alternatively just check out **[this pen](http://codepen.io/Aides/pen/wWKeQe)**. Launch the **[full](http://codepen.io/Aides/full/wWKeQe)** version from your iOS device, add it to your home screen and launch from there.

Environment:
------------

Tested on *iPhone 5* and *iPhone 6* with *iOS 9.1* and *iOS 9.3.2*

Observations:
-------------

* The issue only occurs when launching the page/app from homescreen (pinned app) or inside a Xamarin Webview (might have something to do with UIWebView and WKWebView)
* After changing the device orientation (portrait/landscape) after page load the problem is fixed until the page is reloaded (maybe re-triggering layout fixed it?)
* Changing the lower elements `overflow-y` to `hidden` via JS does fix the problem, however toggling `overflow` causes a repaint causing performance issues
* Removing `height: 100%; width: 100%` from `html, body` fixes the problem as well, however those have to be set for percentage values to work properly

---

Needed is a proper solution / workaround to fix this issue without causing any troublesome side-effects. Also explanation of why this happens would be appreciated.