User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:65.0) Gecko/20100101 Firefox/65.0
Steps to reproduce:
When a DIV has position:absolute and overflow-y:auto and the content of that DIV requires vertical scrollbars, the size of that DIV is not calculated properly. Instead of increasing the width of the DIV, the scrollbar overlaps the content.
The problem can be easily reproduced with this Fiddle: https://jsfiddle.net/catkrwg8/4/
The size of DIV does not change when overflow-y is set to auto. Instead the scrollbar overlaps the content of the DIV, which should not happen.
The size of the DIV should change, when a scrollbar is required. This works as expected in Chrome and Internet Explorer.
Note 1: when the .outer DIV has the .scrollable class initially the size is wrong too.
Note 2: if the .scrollable class would use overflow-y: scroll instead of overflow-y: auto the size of the DIV is calculated correctly.