#011003

CSS

:root {
  --blackn-t: #011003;
  --blackn-t-rgb: 1 16 3;
  --blackn-t-oklch: oklch(0.152 0.041 147.5);
}

.element {
  color: var(--blackn-t);
  background-color: hsl(128 88% 3%);
  border-color: oklch(0.152 0.041 147.5);
}

Tailwind CSS v4

@theme {
  --color-blackn-t: #011003;
  --color-blackn-t-50: #eef9ef;
  --color-blackn-t-100: #dfece1;
  --color-blackn-t-200: #c9d9cb;
  --color-blackn-t-300: #aabeac;
  --color-blackn-t-400: #8fa591;
  --color-blackn-t-500: #758e77;
  --color-blackn-t-600: #637865;
  --color-blackn-t-700: #4f6051;
  --color-blackn-t-800: #3a463a;
  --color-blackn-t-900: #283128;
  --color-blackn-t-950: #161d16;
}

SCSS

$blackn-t: #011003;
$blackn-t-rgb: 1, 16, 3;
$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);
}