Up/down navigation in currently done ignoring transforms (see comment in VisiblePosition::xOffsetForVerticalNavigation() introduced via bug 15671). This is fine inside a transformed element, but we should do something sensible when you arrow down from the bottom of a transformed element.
xOffsetForVerticalNavigation was renamed to lineDirectionPointForVerticalNavigation in below comment: https://github.com/WebKit/WebKit/commit/45dc268cbc88951fcc678624f314a02e48993716 While test case - https://bug-15671-attachments.webkit.org/attachment.cgi?id=25204 seems to work fine for me in Safari 17.5 beta and matching in arrow navigation from top to down and down to top similar to Chrome Canary 125. @Simon & @Vitor - anything else to do here?