Messes up drag-n-drop on all backend pages

Recently noticed that when I used drag-n-drop reordering for the Appearance -> Menus or any other similar backend list, the item I selected would consistently “fly” up get positioned about 500px relative to where my cursor was.

I deactivated all my plugins one-by-one and Instant Images ended up being the culprit. I narrowed it down to the “instant-images.min.css” file.