#010713

CSS

:root {
  --dark-rift: #010713;
  --dark-rift-rgb: 1 7 19;
  --dark-rift-oklch: oklch(0.127 0.032 253);
}

.element {
  color: var(--dark-rift);
  background-color: hsl(220 90% 4%);
  border-color: oklch(0.127 0.032 253);
}

Tailwind CSS v4

@theme {
  --color-dark-rift: #010713;
  --color-dark-rift-50: #eff6fe;
  --color-dark-rift-100: #e1e9f3;
  --color-dark-rift-200: #cbd5e2;
  --color-dark-rift-300: #adb9c8;
  --color-dark-rift-400: #91a0b1;
  --color-dark-rift-500: #77889b;
  --color-dark-rift-600: #657383;
  --color-dark-rift-700: #515c69;
  --color-dark-rift-800: #3a434d;
  --color-dark-rift-900: #282f36;
  --color-dark-rift-950: #161b21;
}

SCSS

$dark-rift: #010713;
$dark-rift-rgb: 1, 7, 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);
}