#11172B

CSS

:root {
  --dark-knight: #11172b;
  --dark-knight-rgb: 17 23 43;
  --dark-knight-oklch: oklch(0.21 0.041 270);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(226 43% 12%);
  border-color: oklch(0.21 0.041 270);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #11172b;
  --color-dark-knight-50: #f1f5ff;
  --color-dark-knight-100: #e3e7f6;
  --color-dark-knight-200: #ced4e6;
  --color-dark-knight-300: #b0b7cd;
  --color-dark-knight-400: #959eb7;
  --color-dark-knight-500: #7b85a2;
  --color-dark-knight-600: #697189;
  --color-dark-knight-700: #535a6e;
  --color-dark-knight-800: #3c4251;
  --color-dark-knight-900: #292e38;
  --color-dark-knight-950: #171a23;
}

SCSS

$dark-knight: #11172b;
$dark-knight-rgb: 17, 23, 43;
$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);
}