#3B5B9F

CSS

:root {
  --blasphemous-blue: #3b5b9f;
  --blasphemous-blue-rgb: 59 91 159;
  --blasphemous-blue-oklch: oklch(0.481 0.116 263.6);
}

.element {
  color: var(--blasphemous-blue);
  background-color: hsl(221 46% 43%);
  border-color: oklch(0.481 0.116 263.6);
}

Tailwind CSS v4

@theme {
  --color-blasphemous-blue: #3b5b9f;
  --color-blasphemous-blue-50: #e5f5ff;
  --color-blasphemous-blue-100: #d6e8ff;
  --color-blasphemous-blue-200: #bdd4ff;
  --color-blasphemous-blue-300: #9bb7f4;
  --color-blasphemous-blue-400: #7b9de3;
  --color-blasphemous-blue-500: #5e84d3;
  --color-blasphemous-blue-600: #5070b2;
  --color-blasphemous-blue-700: #3f598f;
  --color-blasphemous-blue-800: #2b426a;
  --color-blasphemous-blue-900: #1d2d4b;
  --color-blasphemous-blue-950: #0d1a31;
}

SCSS

$blasphemous-blue: #3b5b9f;
$blasphemous-blue-rgb: 59, 91, 159;
$blasphemous-blue-light: mix(#fff, $blasphemous-blue, 20%);
$blasphemous-blue-dark: mix(#000, $blasphemous-blue, 20%);

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