For the "it's the law tho" crowd, here's a fix:

APCA to WCAG 2 Backwards Compatibility Chart

For 4.5:1

Backwards 4.5:1 is achieved when:

IF the lightest color is darker than #d0d0d0
OR the darkest is darker than #595959
THEN Lc ±60 exceeds 4.5:1

ELSE Lc 72 or Lc -77 exceeds 4.5:1 in all cases

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For 3:1

Backwards 3:1 is achieved when:

IF the lightest color is darker than #c4c4c4
OR the darkest is darker than #6c6c6c
THEN Lc ±45 exceeds 3:1

ELSE Lc 57 or Lc -63 exceeds 3:1 in all cases

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Here's the implication:

If both colors are darker than #d0d0d0 or at least one is darker than #595959:

Then it's not a matter of "can you?" use APCA, it's a matter of you *should* use APCA.

For color pairs darker than #d0d0d0, WCAG 2.x contrast math results are not meaningful, and create inaccessible, often unreadable, color pairs.

Actual Accessibility is where it's at.

#darkmode #Webdesign
#a11y #color #webdev
#colour #wcag #apca