Sticky filename header in diff discussions leaves a 2px gap above it

When scrolling down past a diff discussion in the discussion tab (not the changes tab) of a MR, the header will stick to the top to remain visible. However the place it stays leaves a 2px gap above it that is quite ugly and distracting.

Screen_Shot_2019-06-24_at_5.23.07_PM

reproduced on GitLab.com in Chrome 75 and Safari 12.1

Edited by Mike Greiling