#11142A

CSS

:root {
  --dark-knight: #11142a;
  --dark-knight-rgb: 17 20 42;
  --dark-knight-oklch: oklch(0.201 0.044 275.8);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(233 42% 12%);
  border-color: oklch(0.201 0.044 275.8);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #11142a;
  --color-dark-knight-50: #f2f4ff;
  --color-dark-knight-100: #e4e7f7;
  --color-dark-knight-200: #cfd3e7;
  --color-dark-knight-300: #b2b6ce;
  --color-dark-knight-400: #979db9;
  --color-dark-knight-500: #7e84a4;
  --color-dark-knight-600: #6a708a;
  --color-dark-knight-700: #55596f;
  --color-dark-knight-800: #3d4252;
  --color-dark-knight-900: #2a2d39;
  --color-dark-knight-950: #181a23;
}

SCSS

$dark-knight: #11142a;
$dark-knight-rgb: 17, 20, 42;
$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);
}