Created attachment 459832 [details] Test case To reproduce, open the test case and make a selection that spans multiple columns. The first line of a column will not have a selection highlight if the selection extends to the previous column. For example, selecting “Two” through “Five” leaves “Four” unhighlighted. The test case is a reduction from the New York Times Spelling Bee puzzle.
<rdar://problem/94310080>
I am sure, it is now fixed, since I did merge of Blink patch to fix it for Flex and Grid. https://github.com/WebKit/WebKit/commit/48936aafec37b3b17c182f210f46e65bf6df9ba9 I am marking this as duplicate of bug 119878. If it is reproducible, please reopen with screenshot of incorrect behavior. *** This bug has been marked as a duplicate of bug 119878 ***
Thanks for finding the original. Both the test case and the source website behave as expected with the latest shipping Safari on macOS Monterey.