Grapest on Out of the Blue
#880066 on #1199ee
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
3.04:1
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 30.4
Clears Lc 30 — the floor: below this the draft considers text not readable at any size.
Dark text on a lighter ground.
Colour difference
ΔE00 59.7
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#5a0042 is the nearest colour of the same hue that passes AA on #1199ee, 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 4.39:1, ΔE00 38.3.
deuteranopia
Ratio 2.56:1, ΔE00 29.1.
tritanopia
Ratio 1.69:1, ΔE00 63.4.
The weakest of the three is deuteranopia, where the two are ΔE00 29.1 apart against 59.7 for a trichromat — still clearly two colours.
Both colours have pages of their own: Grapest ·Out of the Blue · the same pair the other way round ·all pairs