Chrome Version: 70.0.3524.2
OS: All

Adapted from  issue 674116 

What steps will reproduce the problem?
(1) Open this CodePen https://codepen.io/AlexRad/pen/XMQpvq
(2) Scroll table content

What is the expected result?

Green box should be sticking to top at both columns.

What happens instead?

The green box in the first column does not stick. It does however stick in Firefox and neither box sticks in Safari.

The spec[1] states that "the offset is computed with reference to the nearest ancestor with a scrolling box, or the viewport if no ancestor has a scrolling box." where a scrolling box is created if "Elements and viewports have an associated scrolling box if has a scrolling mechanism or it overflows its content area and the used value of the overflow-x or overflow-y property is hidden." [2]

This seems to suggest that maybe at the moment the content within overflow: hidden overflows the sticky element should use that element, and otherwise it should use the next ancestor up.

[1] https://drafts.csswg.org/css-position/#sticky-pos
[2] https://drafts.csswg.org/cssom-view-1/#scrolling-box