UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.67 Safari/537.36

Steps to reproduce the problem:
1. set body tag overflow to hidden
2. add absolute position element with zIndex to body
3. add 'placeholder' element to increase document height
4. add 'footer' element with background
3. background is invisible

What is the expected behavior?
footer with background

What went wrong?
Footer element without background. Background is visible if remove zIndex.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 70.0.3538.67  Channel: n/a
OS Version: 16.04
Flash Version: 

Not only the background, but also some float elements and borders disappear on my site. But I can't reproduce it.

I attached bug.jpg/expected.png screenshots to show what happen on my site. Initially, the block with comments is in the invisible area of the screen. Float elements and borders appear when I hover the mouse over a button or link (elements with hover state). The bug appeared after updating the browser to version 70.0.3538.67
 

Deleted: index.html 514 bytes

index.html 514 bytes View Download

Deleted: bug.jpg 16.0 KB

	bug.jpg 16.0 KB View Download

Deleted: expected.png 34.5 KB

	expected.png 34.5 KB View Download