Chocolate Castle on God of Rain
#452207 on #4466cc
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
2.71:1
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 23.0
Clears Lc 15 — disabled or purely decorative text, which is not meant to be read.
Dark text on a lighter ground.
Colour difference
ΔE00 45.3
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#ffeadd is the nearest colour of the same hue that passes AA on #4466cc, 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 3.01:1, ΔE00 50.9.
deuteranopia
Ratio 2.56:1, ΔE00 53.2.
tritanopia
Ratio 2.35:1, ΔE00 58.8.
The weakest of the three is protanopia, where the two are ΔE00 50.9 apart against 45.3 for a trichromat — still clearly two colours.
Both colours have pages of their own: Chocolate Castle ·God of Rain · the same pair the other way round ·all pairs