#040C15

CSS

:root {
  --dark-rift: #040c15;
  --dark-rift-rgb: 4 12 21;
  --dark-rift-oklch: oklch(0.15 0.024 248.2);
}

.element {
  color: var(--dark-rift);
  background-color: hsl(212 68% 5%);
  border-color: oklch(0.15 0.024 248.2);
}

Tailwind CSS v4

@theme {
  --color-dark-rift: #040c15;
  --color-dark-rift-50: #f0f6fc;
  --color-dark-rift-100: #e2e9f0;
  --color-dark-rift-200: #cdd5df;
  --color-dark-rift-300: #aeb9c4;
  --color-dark-rift-400: #94a0ac;
  --color-dark-rift-500: #7a8896;
  --color-dark-rift-600: #67737f;
  --color-dark-rift-700: #535c66;
  --color-dark-rift-800: #3c434a;
  --color-dark-rift-900: #292f34;
  --color-dark-rift-950: #171b1f;
}

SCSS

$dark-rift: #040c15;
$dark-rift-rgb: 4, 12, 21;
$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);
}