Dragon’s Fire on Black Box
#fc4a14 on #0f282f
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
4.49:1
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 -38.4
Clears Lc 30 — the floor: below this the draft considers text not readable at any size.
Light text on a darker ground — the negative sign is the polarity.
Colour difference
ΔE00 54.7
different colours
Above 10 — related only in the sense that both are colours.
What the text colour has to become
#fc4a14 is the nearest colour of the same hue that passes AA on #0f282f, 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 2.98:1, ΔE00 39.1.
deuteranopia
Ratio 5.34:1, ΔE00 55.9.
tritanopia
Ratio 7.78:1, ΔE00 80.1.
The weakest of the three is protanopia, where the two are ΔE00 39.1 apart against 54.7 for a trichromat — still clearly two colours.
Both colours have pages of their own: Dragon’s Fire ·Black Box · the same pair the other way round ·all pairs