Bug 255358

Summary: Hairline gaps between elements when using isolation: isolate and mix-blend-mode: plus-lighter
Product: WebKit Reporter: Robert Flack <flackr>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: bfulgham, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari 16   
Hardware: Unspecified   
OS: Unspecified   

Description Robert Flack 2023-04-12 13:07:56 PDT 
Using isolation: isolate on a container with mix-blend-mode: plus-lighter on descendents should result in no gaps between separately composited adjacent elements in the same isolation container. This works on Chrome and Firefox but on Safari there are visible gaps between elements, e.g. https://jsbin.com/norikac/edit?html,css,output

For a simpler example, see https://jsbin.com/jowoken/edit?html,css,output
Or, https://jsbin.com/retafoy/edit?html,css,output for the animation in a paused state showing a visible gap.
Comment 1 Radar WebKit Bug Importer 2023-04-12 15:28:53 PDT 
<rdar://problem/107962749>
Comment 2 Radar WebKit Bug Importer 2023-04-12 15:29:11 PDT 
<rdar://problem/107962770>