Master Sword Blue on Corrosive Green
#00ffee 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
1.46:1
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 -22.1
Clears Lc 15 — disabled or purely decorative text, which is not meant to be read.
Light text on a darker ground — the negative sign is the polarity.
Colour difference
ΔE00 31.0
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#005851 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 1.48:1, ΔE00 28.9.
deuteranopia
Ratio 1.45:1, ΔE00 40.7.
tritanopia
Ratio 1.21:1, ΔE00 6.0.
The weakest of the three is tritanopia, where the two are ΔE00 6.0 apart against 31.0 for a trichromat — still two colours, but a closer call than it looks to you.
Both colours have pages of their own: Master Sword Blue ·Corrosive Green · the same pair the other way round ·all pairs