#3F5897

CSS

:root {
  --blasphemous-blue: #3f5897;
  --blasphemous-blue-rgb: 63 88 151;
  --blasphemous-blue-oklch: oklch(0.472 0.107 266.1);
}

.element {
  color: var(--blasphemous-blue);
  background-color: hsl(223 41% 42%);
  border-color: oklch(0.472 0.107 266.1);
}

Tailwind CSS v4

@theme {
  --color-blasphemous-blue: #3f5897;
  --color-blasphemous-blue-50: #e8f5ff;
  --color-blasphemous-blue-100: #d9e7ff;
  --color-blasphemous-blue-200: #c1d3ff;
  --color-blasphemous-blue-300: #a0b6ef;
  --color-blasphemous-blue-400: #819dde;
  --color-blasphemous-blue-500: #6583cd;
  --color-blasphemous-blue-600: #566fad;
  --color-blasphemous-blue-700: #44598b;
  --color-blasphemous-blue-800: #2f4167;
  --color-blasphemous-blue-900: #202d49;
  --color-blasphemous-blue-950: #101a30;
}

SCSS

$blasphemous-blue: #3f5897;
$blasphemous-blue-rgb: 63, 88, 151;
$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);
}