Quiet Abyss on Pastel Brown
#160435 on #836953
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
3.73:1
Large text only
Not AAA (7:1). Swapping the two colours gives the same number — the ratio does not know which is the text.
APCA
Lc 27.8
Clears Lc 15 — disabled or purely decorative text, which is not meant to be read.
Dark text on a lighter ground.
Colour difference
ΔE00 42.7
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#f1efff is the nearest colour of the same hue that passes AA on #836953, 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 3.61:1, ΔE00 45.2.
deuteranopia
Ratio 3.79:1, ΔE00 47.1.
tritanopia
Ratio 3.98:1, ΔE00 49.9.
The weakest of the three is protanopia, where the two are ΔE00 45.2 apart against 42.7 for a trichromat — still clearly two colours.
Both colours have pages of their own: Quiet Abyss ·Pastel Brown · the same pair the other way round ·all pairs