#0D143B

CSS

:root {
  --infinite-night: #0d143b;
  --infinite-night-rgb: 13 20 59;
  --infinite-night-oklch: oklch(0.213 0.075 270.9);
}

.element {
  color: var(--infinite-night);
  background-color: hsl(231 64% 14%);
  border-color: oklch(0.213 0.075 270.9);
}

Tailwind CSS v4

@theme {
  --color-infinite-night: #0d143b;
  --color-infinite-night-50: #eef4ff;
  --color-infinite-night-100: #dfe7ff;
  --color-infinite-night-200: #c9d3f5;
  --color-infinite-night-300: #aab6df;
  --color-infinite-night-400: #8e9dcc;
  --color-infinite-night-500: #7384b9;
  --color-infinite-night-600: #626f9c;
  --color-infinite-night-700: #4e597d;
  --color-infinite-night-800: #37415d;
  --color-infinite-night-900: #262d41;
  --color-infinite-night-950: #141a2a;
}

SCSS

$infinite-night: #0d143b;
$infinite-night-rgb: 13, 20, 59;
$infinite-night-light: mix(#fff, $infinite-night, 20%);
$infinite-night-dark: mix(#000, $infinite-night, 20%);

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