#13152F

CSS

:root {
  --dark-knight: #13152f;
  --dark-knight-rgb: 19 21 47;
  --dark-knight-oklch: oklch(0.21 0.051 277.7);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(236 42% 13%);
  border-color: oklch(0.21 0.051 277.7);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #13152f;
  --color-dark-knight-50: #f2f4ff;
  --color-dark-knight-100: #e4e6f9;
  --color-dark-knight-200: #cfd2ea;
  --color-dark-knight-300: #b2b5d2;
  --color-dark-knight-400: #979cbd;
  --color-dark-knight-500: #7e83a8;
  --color-dark-knight-600: #6a6f8e;
  --color-dark-knight-700: #555972;
  --color-dark-knight-800: #3d4154;
  --color-dark-knight-900: #2a2d3b;
  --color-dark-knight-950: #181a25;
}

SCSS

$dark-knight: #13152f;
$dark-knight-rgb: 19, 21, 47;
$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);
}