#29324D

CSS

:root {
  --mediaeval-blue: #29324d;
  --mediaeval-blue-rgb: 41 50 77;
  --mediaeval-blue-oklch: oklch(0.322 0.05 269.4);
}

.element {
  color: var(--mediaeval-blue);
  background-color: hsl(225 31% 23%);
  border-color: oklch(0.322 0.05 269.4);
}

Tailwind CSS v4

@theme {
  --color-mediaeval-blue: #29324d;
  --color-mediaeval-blue-50: #f0f5ff;
  --color-mediaeval-blue-100: #e2e7f9;
  --color-mediaeval-blue-200: #ccd4ea;
  --color-mediaeval-blue-300: #aeb7d2;
  --color-mediaeval-blue-400: #929ebd;
  --color-mediaeval-blue-500: #7985a8;
  --color-mediaeval-blue-600: #66718e;
  --color-mediaeval-blue-700: #525a72;
  --color-mediaeval-blue-800: #3b4254;
  --color-mediaeval-blue-900: #282e3b;
  --color-mediaeval-blue-950: #161a25;
}

SCSS

$mediaeval-blue: #29324d;
$mediaeval-blue-rgb: 41, 50, 77;
$mediaeval-blue-light: mix(#fff, $mediaeval-blue, 20%);
$mediaeval-blue-dark: mix(#000, $mediaeval-blue, 20%);

.element {
  color: $mediaeval-blue;
  box-shadow: 0 0 0 2px rgba($mediaeval-blue, 0.35);
}