#181B2F

CSS

:root {
  --dark-knight: #181b2f;
  --dark-knight-rgb: 24 27 47;
  --dark-knight-oklch: oklch(0.23 0.039 276.4);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(232 32% 14%);
  border-color: oklch(0.23 0.039 276.4);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #181b2f;
  --color-dark-knight-50: #f2f4ff;
  --color-dark-knight-100: #e4e7f5;
  --color-dark-knight-200: #d0d3e5;
  --color-dark-knight-300: #b2b6cc;
  --color-dark-knight-400: #989db6;
  --color-dark-knight-500: #7f84a0;
  --color-dark-knight-600: #6b7088;
  --color-dark-knight-700: #565a6d;
  --color-dark-knight-800: #3e4250;
  --color-dark-knight-900: #2b2d38;
  --color-dark-knight-950: #181a22;
}

SCSS

$dark-knight: #181b2f;
$dark-knight-rgb: 24, 27, 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);
}