Look at http://jsbin.com/suwibimesu in iPhone (I used iPhone 6 Plus). There are begin-mark, input, some divs and end-mark on the example page. Steps: 1. Set focus to input 2. Start scrolling down with sharp gestures Expected: scroll to end-mark Actual: you can't reach the end-mark (very often) Rarely it can be reproduced without focusing input. Steps: 1. Close keyboard with "Done" 2. Start scrolling down with sharp gestures Expected and Actual as is case before. The code is here http://jsbin.com/suwibimesu/edit?html,css,output
What iOS version are you reporting this with?
I mention it in header - 10.3