User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.99 Safari/537.36
Steps to reproduce:
Create a parent element with "position: absolute", "top: 0", "left: 0", "right: 0", "bottom: 0", "overflow-y: auto", and "padding: 60px".
Then, give it a child element with "padding-bottom: 60px", and enough text content to overflow the parent and cause a scrolling behavior.
As seen here: http://jsfiddle.net/8nyh510w/3/
The bottom paddings of the parent and child collapse and overlap each other. This is NOT the behavior in Chrome or IE11.
The child's bottom padding should sit underneath the text content, inside the parent's content box, resulting in more scrollable area. The child's bottom padding should NOT collapse into the parent's bottom padding.
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:44.0) Gecko/20100101 Firefox/44.0
I get the same result in IE 11.
*** This bug has been marked as a duplicate of bug 748518 ***