UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Example URL:
http://repetitors.info

Steps to reproduce the problem:
1. Open website on ios mobile device
2. Pull page down until pull-to-refresh menu appears
3. quickly pull page up, but not refresh page

What is the expected behavior?
fixed block with top:0 expected to be on top of page

What went wrong?
fixed block top will become some random number.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? No 

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 52.0.2743.84  Channel: n/a
OS Version: OS X 9.3.1
Flash Version: Shockwave Flash 23.0 r0