Pompelmo

#ff6666

A red that is saturated. It is light — black text sits on it comfortably, white text does not.

Hex

#ff6666

RGB

255, 102, 102

OKLCh

70.4% 0.187 23.2°

CIELAB (D50)

63.8, 59.3, 31.9

What is true of this colour, and of no other

3 other named colours sit within ΔE00 2 of it.
It sits exactly on the sRGB boundary: at this lightness and hue the gamut has nothing left, and a wider display would show a more colourful version of it.
As text on white it measures APCA Lc 53.9; on black, Lc -47.9. The sign is the polarity, which the WCAG ratio discards.
Built into an eleven-step scale, 10 of the 10 adjacent pairs stay ΔE00 2 apart — see the ramp.
protanopia and deuteranopia and tritanopia shift it by ΔE00 35.4 and 42.3 and 52.2 — no red cone.

Text on this colour

White text

2.86:1 — fails AA

Black text

7.34:1 — passes AA

Black text is the better of the two at7.34:1. That is enough for body text.

As text on white, it needs to change

#d63f45 is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved.

Try it against your own background

The same colour, with one cone missing

As you see it

#ff6666

protanopia

#848467 · ΔE00 35.4

deuteranopia

#a7a75f · ΔE00 42.3

tritanopia

#c5c500 · ΔE00 52.2

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isFusion Red at ΔE00 0.866: below 1.0 — an ordinary observer cannot tell these apart, even side by side. What the numbers mean.

4 of these have no page of their own: pages exist for the 4,961 colours the dataset marks as good names.