Created attachment 377102 [details] [Image] Screenshot of Issue .
Created attachment 377103 [details] Patch
Created attachment 377104 [details] [Image] After Patch is applied I'm not sure how to "calculate" a corresponding dark mode color for a given light mode color (or pair of colors, such as the two in the checkerboard), but this looked fine to me :)
Comment on attachment 377103 [details] Patch r=me
Comment on attachment 377103 [details] Patch Clearing flags on attachment: 377103 Committed r249057: <https://trac.webkit.org/changeset/249057>
All reviewed patches have been landed. Closing bug.
<rdar://problem/54647928>