Kelp on Olympian Blue
#4d503c on #1c4c8c
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
1.03:1
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 34.7
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#bbbfa8 is the nearest colour of the same hue that passes AA on #1c4c8c, 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 1.02:1, ΔE00 34.8.
deuteranopia
Ratio 1.05:1, ΔE00 35.8.
tritanopia
Ratio 1.04:1, ΔE00 34.1.
The weakest of the three is tritanopia, where the two are ΔE00 34.1 apart against 34.7 for a trichromat — still clearly two colours.
Both colours have pages of their own: Kelp ·Olympian Blue · the same pair the other way round ·all pairs