Wild Thing on Acoustic Brown
#654243 on #766b69
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
1.69:1
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 12.3
Below Lc 15: the draft treats this as not text.
Dark text on a lighter ground.
Colour difference
ΔE00 16.0
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#ffebeb is the nearest colour of the same hue that passes AA on #766b69, 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 1.78:1, ΔE00 13.3.
deuteranopia
Ratio 1.65:1, ΔE00 12.3.
tritanopia
Ratio 1.52:1, ΔE00 10.8.
The weakest of the three is tritanopia, where the two are ΔE00 10.8 apart against 16.0 for a trichromat — still clearly two colours.
Both colours have pages of their own: Wild Thing ·Acoustic Brown · the same pair the other way round ·all pairs