#16152D

CSS

:root {
  --dark-knight: #16152d;
  --dark-knight-rgb: 22 21 45;
  --dark-knight-oklch: oklch(0.211 0.047 283.5);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(243 36% 13%);
  border-color: oklch(0.211 0.047 283.5);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #16152d;
  --color-dark-knight-50: #f3f4ff;
  --color-dark-knight-100: #e6e6f7;
  --color-dark-knight-200: #d2d2e8;
  --color-dark-knight-300: #b5b4cf;
  --color-dark-knight-400: #9a9bba;
  --color-dark-knight-500: #8283a5;
  --color-dark-knight-600: #6e6f8b;
  --color-dark-knight-700: #585870;
  --color-dark-knight-800: #3f4152;
  --color-dark-knight-900: #2c2d39;
  --color-dark-knight-950: #191a24;
}

SCSS

$dark-knight: #16152d;
$dark-knight-rgb: 22, 21, 45;
$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);
}