About red-900
#82181A is red-900, a tailwind v4. This page shows its rgb(130, 24, 26) / hsl(358.87, 68.83%, 30.2%) / oklch(0.3967 0.1408 25.71) 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.