#040D00

CSS

:root {
  --blackn-t: #040d00;
  --blackn-t-rgb: 4 13 0;
  --blackn-t-oklch: oklch(0.143 0.04 133.1);
}

.element {
  color: var(--blackn-t);
  background-color: hsl(102 100% 3%);
  border-color: oklch(0.143 0.04 133.1);
}

Tailwind CSS v4

@theme {
  --color-blackn-t: #040d00;
  --color-blackn-t-50: #f0f8ec;
  --color-blackn-t-100: #e2ebde;
  --color-blackn-t-200: #cdd8c7;
  --color-blackn-t-300: #afbca8;
  --color-blackn-t-400: #95a48c;
  --color-blackn-t-500: #7c8c71;
  --color-blackn-t-600: #697760;
  --color-blackn-t-700: #545f4c;
  --color-blackn-t-800: #3d4537;
  --color-blackn-t-900: #2a3025;
  --color-blackn-t-950: #181c14;
}

SCSS

$blackn-t: #040d00;
$blackn-t-rgb: 4, 13, 0;
$blackn-t-light: mix(#fff, $blackn-t, 20%);
$blackn-t-dark: mix(#000, $blackn-t, 20%);

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