229408 2021-08-23 04:54:54 -0700 Element rendered in the wrong place after sibling causes some layout changes 2021-08-24 20:42:09 -0700 1 1 1 Unclassified WebKit Compositing Safari Technology Preview Unspecified Unspecified NEW InRadar P2 Normal --- 1 tomc webkit-unassigned koivisto simon.fraser webkit-bug-importer zalan oldest_to_newest 1786393 0 tomc 2021-08-23 04:54:54 -0700 See this Codesandbox example: https://zmslt.csb.app - Note the magenta box in the center bottom of the screen - Click on the image (to enlarge it, it simply removes the explicit width/height on the img) - Notice how the magenta box shifts to the top left. Safari Technology Preview, Release 130 (Safari 15.0, WebKit 16612.1.26.1.5) It works correctly when you: - comment out the 'inset: 0;' line in .overlay - comment out the 'display: flex;' line in .overlay - comment out the 'overflow: auto;' line in .content - comment out the 'flex: 100% 0 1;' line in .content 1786843 1 webkit-bug-importer 2021-08-24 11:31:00 -0700 <rdar://problem/82301706> 1787072 2 zalan 2021-08-24 20:42:09 -0700 This looks like a composition/painting issue on the fixed element (offsetTop/Left returns the correct value and toggling composition borders fixes the issue).