#2B2437

CSS

:root {
  --black-velvet: #2b2437;
  --black-velvet-rgb: 43 36 55;
  --black-velvet-oklch: oklch(0.277 0.036 301);
}

.element {
  color: var(--black-velvet);
  background-color: hsl(262 21% 18%);
  border-color: oklch(0.277 0.036 301);
}

Tailwind CSS v4

@theme {
  --color-black-velvet: #2b2437;
  --color-black-velvet-50: #f7f3fe;
  --color-black-velvet-100: #eae5f2;
  --color-black-velvet-200: #d7d1e1;
  --color-black-velvet-300: #bbb3c7;
  --color-black-velvet-400: #a29ab1;
  --color-black-velvet-500: #8a819b;
  --color-black-velvet-600: #756d83;
  --color-black-velvet-700: #5d5769;
  --color-black-velvet-800: #44404d;
  --color-black-velvet-900: #2f2c36;
  --color-black-velvet-950: #1b1921;
}

SCSS

$black-velvet: #2b2437;
$black-velvet-rgb: 43, 36, 55;
$black-velvet-light: mix(#fff, $black-velvet, 20%);
$black-velvet-dark: mix(#000, $black-velvet, 20%);

.element {
  color: $black-velvet;
  box-shadow: 0 0 0 2px rgba($black-velvet, 0.35);
}