About zinc-900
#18181B is zinc-900, a tailwind v4. This page shows its rgb(24, 24, 27) / hsl(240, 5.88%, 10%) / oklch(0.2103 0.0059 285.89) values, WCAG contrast against black and white, an OKLCH tint-and-shade ramp, and complementary, analogous, and triadic harmonies — all computed in perceptually-uniform OKLCH.