DCI-P3

DCI-P3 comes from digital cinema. Display P3 is the variant used by computers and phones: CSS Color 4 states that it uses the same primary chromaticities as DCI-P3, but with a D65 white point, the same white as sRGB, and the sRGB transfer curve. Its primaries are red at x 0.680, y 0.320, green at 0.265, 0.690 and blue at 0.150, 0.060, so its red and green reach further than sRGB's while the blue primary is the same.

On a spec sheet, a DCI-P3 coverage figure says how much of that triangle the panel reaches. Two screens quoted at the same percentage can still differ, because coverage says nothing about accuracy. CSS Color 4 notes that modern displays, TVs, laptop and phone screens can show all or nearly all of the display-p3 gamut.

A browser reports p3 from the color-gamut media query when the system gives it approximately that gamut or more, and CSS can name Display P3 colours with color(display-p3 ...). The colour gamut test reads both and draws P3 colours next to the most saturated sRGB ones so you can see whether the wider colour reaches your eyes. It cannot measure the panel's coverage; that needs a colorimeter.