Created attachment 451777 [details] testcase-scroll-y In a unidirectional scroll-snap container, scrolling sideways with a trackpad during overscroll causes the scroll container to scroll in that "forbidden" direction, although no content is overflowing, and even with `overflow-x` or `overflow-y` set explicitly to `hidden`. See the attached testcases for scroll container on the y and x axis. See also a video for the y axis. Steps to reproduce: - open the testcase file for the y axis - scroll about half the content, then in another gesture scroll all the way down to cause overscroll - without lifting the finger, scroll sideways (left or right) - see the scroll content move in a forbidden direction The expected behaviour is that the content does not move in that direction, it must only be allowed to move in the defined scroll direction. I started to see this behaviour a few Safari TP versions back, possibly around version 137.
Created attachment 451778 [details] testcase-scroll-x
Created attachment 451779 [details] video-scroll-y
Is scrolling in the unwanted direction just rubber-banding (aka overscroll)?
Yes it is just rubber-banding indeed, it goes back into place afterwards.
<rdar://problem/89184230>