Purple Climax on Opera
#8800ff on #816575
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
1.16:1
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 0.0
Below Lc 15: the draft treats this as not text.
Too close to call.
Colour difference
ΔE00 29.1
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#f1edff is the nearest colour of the same hue that passes AA on #816575, 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 1.30:1, ΔE00 27.5.
deuteranopia
Ratio 1.10:1, ΔE00 27.6.
tritanopia
Ratio 1.17:1, ΔE00 45.7.
The weakest of the three is protanopia, where the two are ΔE00 27.5 apart against 29.1 for a trichromat — still clearly two colours.
Both colours have pages of their own: Purple Climax ·Opera · the same pair the other way round ·all pairs