#2E37A9

CSS

:root {
  --depths-of-night: #2e37a9;
  --depths-of-night-rgb: 46 55 169;
  --depths-of-night-oklch: oklch(0.41 0.179 272);
}

.element {
  color: var(--depths-of-night);
  background-color: hsl(236 57% 42%);
  border-color: oklch(0.41 0.179 272);
}

Tailwind CSS v4

@theme {
  --color-depths-of-night: #2e37a9;
  --color-depths-of-night-50: #e5f2ff;
  --color-depths-of-night-100: #d5e4ff;
  --color-depths-of-night-200: #bccfff;
  --color-depths-of-night-300: #9bafff;
  --color-depths-of-night-400: #7b94ff;
  --color-depths-of-night-500: #6076fb;
  --color-depths-of-night-600: #5165d3;
  --color-depths-of-night-700: #4051aa;
  --color-depths-of-night-800: #2b3b7f;
  --color-depths-of-night-900: #1d295a;
  --color-depths-of-night-950: #0e163d;
}

SCSS

$depths-of-night: #2e37a9;
$depths-of-night-rgb: 46, 55, 169;
$depths-of-night-light: mix(#fff, $depths-of-night, 20%);
$depths-of-night-dark: mix(#000, $depths-of-night, 20%);

.element {
  color: $depths-of-night;
  box-shadow: 0 0 0 2px rgba($depths-of-night, 0.35);
}