Purple Climax on Hint of Blue
#8800ff on #cee1f2
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
4.49:1
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 58.3
Clears Lc 45 — large or heavy display text.
Dark text on a lighter ground.
Colour difference
ΔE00 42.3
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#8800ff is the nearest colour of the same hue that passes AA on #cee1f2, 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 5.40:1, ΔE00 52.3.
deuteranopia
Ratio 4.11:1, ΔE00 43.7.
tritanopia
Ratio 4.18:1, ΔE00 36.7.
The weakest of the three is tritanopia, where the two are ΔE00 36.7 apart against 42.3 for a trichromat — still clearly two colours.
Both colours have pages of their own: Purple Climax ·Hint of Blue · the same pair the other way round ·all pairs