Function initial_ink 

pub fn initial_ink(fill: AlphaColor<Srgb>, theme: &Theme) -> AlphaColor<Srgb>

The initials ink on fill.

One direction per presence palette ([dark_initials]). The ink takes the fill’s own hue, as deep (or as pale) as it must be to reach small-text contrast (7:1) on that fill, or the extreme where it cannot.