Panorama on Corrosive Green
#327a88 on #54d905
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
2.64:1
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 37.2
Clears Lc 30 — the floor: below this the draft considers text not readable at any size.
Dark text on a lighter ground.
Colour difference
ΔE00 46.7
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#005663 is the nearest colour of the same hue that passes AA on #54d905, 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 2.73:1, ΔE00 48.6.
deuteranopia
Ratio 2.60:1, ΔE00 51.5.
tritanopia
Ratio 2.34:1, ΔE00 23.8.
The weakest of the three is tritanopia, where the two are ΔE00 23.8 apart against 46.7 for a trichromat — still clearly two colours.
Both colours have pages of their own: Panorama ·Corrosive Green · the same pair the other way round ·all pairs