#040A12

CSS

:root {
  --dark-rift: #040a12;
  --dark-rift-rgb: 4 10 18;
  --dark-rift-oklch: oklch(0.142 0.021 250.6);
}

.element {
  color: var(--dark-rift);
  background-color: hsl(214 64% 4%);
  border-color: oklch(0.142 0.021 250.6);
}

Tailwind CSS v4

@theme {
  --color-dark-rift: #040a12;
  --color-dark-rift-50: #f1f6fb;
  --color-dark-rift-100: #e3e8ef;
  --color-dark-rift-200: #ced5dd;
  --color-dark-rift-300: #b0b8c2;
  --color-dark-rift-400: #95a0ab;
  --color-dark-rift-500: #7c8894;
  --color-dark-rift-600: #69737d;
  --color-dark-rift-700: #545c64;
  --color-dark-rift-800: #3d434a;
  --color-dark-rift-900: #2a2e33;
  --color-dark-rift-950: #171b1f;
}

SCSS

$dark-rift: #040a12;
$dark-rift-rgb: 4, 10, 18;
$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);
}