#0E162F

CSS

:root {
  --dark-knight: #0e162f;
  --dark-knight-rgb: 14 22 47;
  --dark-knight-oklch: oklch(0.208 0.051 268.4);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(225 54% 12%);
  border-color: oklch(0.208 0.051 268.4);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #0e162f;
  --color-dark-knight-50: #eff5ff;
  --color-dark-knight-100: #e1e7fa;
  --color-dark-knight-200: #ccd4eb;
  --color-dark-knight-300: #adb7d2;
  --color-dark-knight-400: #929ebd;
  --color-dark-knight-500: #7885a9;
  --color-dark-knight-600: #65718f;
  --color-dark-knight-700: #515a72;
  --color-dark-knight-800: #3a4254;
  --color-dark-knight-900: #282e3b;
  --color-dark-knight-950: #161a25;
}

SCSS

$dark-knight: #0e162f;
$dark-knight-rgb: 14, 22, 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);
}