UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.101 Safari/537.36

Steps to reproduce the problem:
1. Visit https://codepen.io/anon/pen/ZJjbKO
2. Scroll the element.
3. Remove comment around position: relative;
4. Scroll the element.

What is the expected behavior?
A parents fixed positioning shouldn't affect the positioning of the sticky elements.

Works as expected in Firefox.

What went wrong?
The sticky elements aren't visible at the location that they are positioned (if highlighted in the elements pane in devtools). They are visible at a seemingly random offset

The following issue might be related: https://bugs.chromium.org/p/chromium/issues/detail?id=686164

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 60.0.3112.101  Channel: stable
OS Version: OS X 10.12.5
Flash Version: Shockwave Flash 26.0 r0