Olympian Blue on Memorial Black
#1c4c8c on #091101
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
2.25:1
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 -12.9
Below Lc 15: the draft treats this as not text.
Light text on a darker ground — the negative sign is the polarity.
Colour difference
ΔE00 34.5
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#4b7cc0 is the nearest colour of the same hue that passes AA on #091101, 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 2.36:1, ΔE00 35.9.
deuteranopia
Ratio 2.20:1, ΔE00 35.4.
tritanopia
Ratio 2.23:1, ΔE00 28.6.
The weakest of the three is tritanopia, where the two are ΔE00 28.6 apart against 34.5 for a trichromat — still clearly two colours.
Both colours have pages of their own: Olympian Blue ·Memorial Black · the same pair the other way round ·all pairs