Florida’s Alligator on Ms. Pac-Man Kiss
#664422 on #ff00aa
Body text at this size
And the smaller size most interfaces actually use for paragraphs — the size that decides whether a pair is usable.
Caption text, which almost nothing passes.
WCAG 2.1
2.42:1
Fails AA
Not AAA (7:1). Swapping the two colours gives the same number — the ratio does not know which is the text.
APCA
Lc 26.9
Clears Lc 15 — disabled or purely decorative text, which is not meant to be read.
Dark text on a lighter ground.
Colour difference
ΔE00 45.6
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#341a00 is the nearest colour of the same hue that passes AA on #ff00aa, at 4.50:1. Only the lightness moved, and some chroma was given up to stay inside sRGB — which is the point: your colour stays recognisably your colour.
And to someone missing a cone
protanopia
Ratio 1.63:1, ΔE00 44.5.
deuteranopia
Ratio 2.79:1, ΔE00 39.7.
tritanopia
Ratio 3.68:1, ΔE00 37.1.
The weakest of the three is tritanopia, where the two are ΔE00 37.1 apart against 45.6 for a trichromat — still clearly two colours.
Both colours have pages of their own: Florida’s Alligator ·Ms. Pac-Man Kiss · the same pair the other way round ·all pairs