#01192E

CSS

:root {
  --oxford-by-night: #01192e;
  --oxford-by-night-rgb: 1 25 46;
  --oxford-by-night-oklch: oklch(0.207 0.052 247);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(208 96% 9%);
  border-color: oklch(0.207 0.052 247);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #01192e;
  --color-oxford-by-night-50: #eaf7ff;
  --color-oxford-by-night-100: #dbeaf9;
  --color-oxford-by-night-200: #c4d7ea;
  --color-oxford-by-night-300: #a3bad2;
  --color-oxford-by-night-400: #86a2bc;
  --color-oxford-by-night-500: #6a8aa7;
  --color-oxford-by-night-600: #5a758d;
  --color-oxford-by-night-700: #485d71;
  --color-oxford-by-night-800: #334553;
  --color-oxford-by-night-900: #232f3a;
  --color-oxford-by-night-950: #121c24;
}

SCSS

$oxford-by-night: #01192e;
$oxford-by-night-rgb: 1, 25, 46;
$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);
}