#041322

CSS

:root {
  --oxford-by-night: #041322;
  --oxford-by-night-rgb: 4 19 34;
  --oxford-by-night-oklch: oklch(0.182 0.038 248.7);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(210 79% 7%);
  border-color: oklch(0.182 0.038 248.7);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #041322;
  --color-oxford-by-night-50: #edf6ff;
  --color-oxford-by-night-100: #dfe9f5;
  --color-oxford-by-night-200: #c9d6e4;
  --color-oxford-by-night-300: #a9b9cb;
  --color-oxford-by-night-400: #8da1b4;
  --color-oxford-by-night-500: #73899f;
  --color-oxford-by-night-600: #617486;
  --color-oxford-by-night-700: #4e5d6c;
  --color-oxford-by-night-800: #38444f;
  --color-oxford-by-night-900: #262f37;
  --color-oxford-by-night-950: #151b22;
}

SCSS

$oxford-by-night: #041322;
$oxford-by-night-rgb: 4, 19, 34;
$oxford-by-night-light: mix(#fff, $oxford-by-night, 20%);
$oxford-by-night-dark: mix(#000, $oxford-by-night, 20%);

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