Endless Galaxy on Olympian Blue
#000044 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
2.27:1
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 13.7
Below Lc 15: the draft treats this as not text.
Dark text on a lighter ground.
Colour difference
ΔE00 22.9
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#9cbcff is the nearest colour of the same hue that passes AA on #1c4c8c, 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 2.39:1, ΔE00 20.7.
deuteranopia
Ratio 2.21:1, ΔE00 19.0.
tritanopia
Ratio 2.24:1, ΔE00 20.2.
The weakest of the three is deuteranopia, where the two are ΔE00 19.0 apart against 22.9 for a trichromat — still clearly two colours.
Both colours have pages of their own: Endless Galaxy ·Olympian Blue · the same pair the other way round ·all pairs