#010711

CSS

:root {
  --dark-rift: #010711;
  --dark-rift-rgb: 1 7 17;
  --dark-rift-oklch: oklch(0.126 0.028 249.2);
}

.element {
  color: var(--dark-rift);
  background-color: hsl(218 89% 4%);
  border-color: oklch(0.126 0.028 249.2);
}

Tailwind CSS v4

@theme {
  --color-dark-rift: #010711;
  --color-dark-rift-50: #eff6fd;
  --color-dark-rift-100: #e1e9f1;
  --color-dark-rift-200: #ccd5e0;
  --color-dark-rift-300: #adb9c6;
  --color-dark-rift-400: #92a0af;
  --color-dark-rift-500: #788899;
  --color-dark-rift-600: #667381;
  --color-dark-rift-700: #515c67;
  --color-dark-rift-800: #3b434c;
  --color-dark-rift-900: #282f35;
  --color-dark-rift-950: #161b20;
}

SCSS

$dark-rift: #010711;
$dark-rift-rgb: 1, 7, 17;
$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);
}