#15122A

CSS

:root {
  --dark-knight: #15122a;
  --dark-knight-rgb: 21 18 42;
  --dark-knight-oklch: oklch(0.2 0.047 287.1);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(248 40% 12%);
  border-color: oklch(0.2 0.047 287.1);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #15122a;
  --color-dark-knight-50: #f4f3ff;
  --color-dark-knight-100: #e7e6f7;
  --color-dark-knight-200: #d3d1e8;
  --color-dark-knight-300: #b6b4cf;
  --color-dark-knight-400: #9c9bb9;
  --color-dark-knight-500: #8482a4;
  --color-dark-knight-600: #6f6e8b;
  --color-dark-knight-700: #59586f;
  --color-dark-knight-800: #404052;
  --color-dark-knight-900: #2c2c39;
  --color-dark-knight-950: #191924;
}

SCSS

$dark-knight: #15122a;
$dark-knight-rgb: 21, 18, 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);
}