#171129

CSS

:root {
  --dark-knight: #171129;
  --dark-knight-rgb: 23 17 41;
  --dark-knight-oklch: oklch(0.199 0.047 293.2);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(255 41% 11%);
  border-color: oklch(0.199 0.047 293.2);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #171129;
  --color-dark-knight-50: #f6f3ff;
  --color-dark-knight-100: #e9e5f6;
  --color-dark-knight-200: #d5d1e7;
  --color-dark-knight-300: #b9b3ce;
  --color-dark-knight-400: #9f9ab8;
  --color-dark-knight-500: #8781a3;
  --color-dark-knight-600: #726d8a;
  --color-dark-knight-700: #5b576e;
  --color-dark-knight-800: #424052;
  --color-dark-knight-900: #2e2c39;
  --color-dark-knight-950: #1a1923;
}

SCSS

$dark-knight: #171129;
$dark-knight-rgb: 23, 17, 41;
$dark-knight-light: mix(#fff, $dark-knight, 20%);
$dark-knight-dark: mix(#000, $dark-knight, 20%);

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