Memorial Black on God of Rain
#091101 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
3.68:1
Large text only
Not AAA (7:1). Swapping the two colours gives the same number — the ratio does not know which is the text.
APCA
Lc 28.0
Clears Lc 15 — disabled or purely decorative text, which is not meant to be read.
Dark text on a lighter ground.
Colour difference
ΔE00 44.5
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#e5f2d7 is the nearest colour of the same hue that passes AA on #4466cc, at 4.50:1. Only the lightness moved — which is the point: your colour stays recognisably your colour.
And to someone missing a cone
protanopia
Ratio 3.81:1, ΔE00 45.8.
deuteranopia
Ratio 3.61:1, ΔE00 44.8.
tritanopia
Ratio 3.65:1, ΔE00 37.6.
The weakest of the three is tritanopia, where the two are ΔE00 37.6 apart against 44.5 for a trichromat — still clearly two colours.
Both colours have pages of their own: Memorial Black ·God of Rain · the same pair the other way round ·all pairs