#040913

CSS

:root {
  --dark-rift: #040913;
  --dark-rift-rgb: 4 9 19;
  --dark-rift-oklch: oklch(0.139 0.025 258.5);
}

.element {
  color: var(--dark-rift);
  background-color: hsl(220 65% 5%);
  border-color: oklch(0.139 0.025 258.5);
}

Tailwind CSS v4

@theme {
  --color-dark-rift: #040913;
  --color-dark-rift-50: #f1f5fc;
  --color-dark-rift-100: #e3e8f0;
  --color-dark-rift-200: #ced5df;
  --color-dark-rift-300: #b0b8c4;
  --color-dark-rift-400: #969fad;
  --color-dark-rift-500: #7c8797;
  --color-dark-rift-600: #697280;
  --color-dark-rift-700: #545b66;
  --color-dark-rift-800: #3d434b;
  --color-dark-rift-900: #2a2e34;
  --color-dark-rift-950: #171b20;
}

SCSS

$dark-rift: #040913;
$dark-rift-rgb: 4, 9, 19;
$dark-rift-light: mix(#fff, $dark-rift, 20%);
$dark-rift-dark: mix(#000, $dark-rift, 20%);

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