#221D2E

CSS

:root {
  --black-velvet: #221d2e;
  --black-velvet-rgb: 34 29 46;
  --black-velvet-oklch: oklch(0.245 0.033 297.5);
}

.element {
  color: var(--black-velvet);
  background-color: hsl(258 23% 15%);
  border-color: oklch(0.245 0.033 297.5);
}

Tailwind CSS v4

@theme {
  --color-black-velvet: #221d2e;
  --color-black-velvet-50: #f6f3fd;
  --color-black-velvet-100: #e9e6f1;
  --color-black-velvet-200: #d6d1e1;
  --color-black-velvet-300: #b9b4c6;
  --color-black-velvet-400: #a09bb0;
  --color-black-velvet-500: #88829a;
  --color-black-velvet-600: #736e82;
  --color-black-velvet-700: #5c5868;
  --color-black-velvet-800: #43404d;
  --color-black-velvet-900: #2e2c35;
  --color-black-velvet-950: #1b1920;
}

SCSS

$black-velvet: #221d2e;
$black-velvet-rgb: 34, 29, 46;
$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);
}