#041523

CSS

:root {
  --oxford-by-night: #041523;
  --oxford-by-night-rgb: 4 21 35;
  --oxford-by-night-oklch: oklch(0.189 0.037 244.5);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(207 79% 8%);
  border-color: oklch(0.189 0.037 244.5);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #041523;
  --color-oxford-by-night-50: #edf6ff;
  --color-oxford-by-night-100: #dee9f4;
  --color-oxford-by-night-200: #c8d6e4;
  --color-oxford-by-night-300: #a9baca;
  --color-oxford-by-night-400: #8ca1b3;
  --color-oxford-by-night-500: #72899e;
  --color-oxford-by-night-600: #607485;
  --color-oxford-by-night-700: #4d5d6b;
  --color-oxford-by-night-800: #37444e;
  --color-oxford-by-night-900: #262f37;
  --color-oxford-by-night-950: #141c21;
}

SCSS

$oxford-by-night: #041523;
$oxford-by-night-rgb: 4, 21, 35;
$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);
}