#071E33

CSS

:root {
  --oxford-by-night: #071e33;
  --oxford-by-night-rgb: 7 30 51;
  --oxford-by-night-oklch: oklch(0.229 0.05 249);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(209 76% 11%);
  border-color: oklch(0.229 0.05 249);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #071e33;
  --color-oxford-by-night-50: #ebf7ff;
  --color-oxford-by-night-100: #dceaf9;
  --color-oxford-by-night-200: #c5d6e9;
  --color-oxford-by-night-300: #a5bad1;
  --color-oxford-by-night-400: #88a1bb;
  --color-oxford-by-night-500: #6d89a6;
  --color-oxford-by-night-600: #5c748d;
  --color-oxford-by-night-700: #495d71;
  --color-oxford-by-night-800: #344453;
  --color-oxford-by-night-900: #242f3a;
  --color-oxford-by-night-950: #131c24;
}

SCSS

$oxford-by-night: #071e33;
$oxford-by-night-rgb: 7, 30, 51;
$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);
}