#001E30

CSS

:root {
  --oxford-by-night: #001e30;
  --oxford-by-night-rgb: 0 30 48;
  --oxford-by-night-oklch: oklch(0.224 0.05 238.8);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(203 100% 9%);
  border-color: oklch(0.224 0.05 238.8);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #001e30;
  --color-oxford-by-night-50: #e9f7ff;
  --color-oxford-by-night-100: #daebf7;
  --color-oxford-by-night-200: #c2d8e8;
  --color-oxford-by-night-300: #a1bbcf;
  --color-oxford-by-night-400: #84a3b9;
  --color-oxford-by-night-500: #678ba4;
  --color-oxford-by-night-600: #58768b;
  --color-oxford-by-night-700: #465e6f;
  --color-oxford-by-night-800: #324552;
  --color-oxford-by-night-900: #223039;
  --color-oxford-by-night-950: #111c23;
}

SCSS

$oxford-by-night: #001e30;
$oxford-by-night-rgb: 0, 30, 48;
$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);
}