#00192C

CSS

:root {
  --oxford-by-night: #00192c;
  --oxford-by-night-rgb: 0 25 44;
  --oxford-by-night-oklch: oklch(0.205 0.05 243.4);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(206 100% 9%);
  border-color: oklch(0.205 0.05 243.4);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #00192c;
  --color-oxford-by-night-50: #eaf7ff;
  --color-oxford-by-night-100: #dbeaf8;
  --color-oxford-by-night-200: #c3d7e9;
  --color-oxford-by-night-300: #a3bbd0;
  --color-oxford-by-night-400: #86a2ba;
  --color-oxford-by-night-500: #6a8aa5;
  --color-oxford-by-night-600: #5a758c;
  --color-oxford-by-night-700: #475e70;
  --color-oxford-by-night-800: #334552;
  --color-oxford-by-night-900: #233039;
  --color-oxford-by-night-950: #121c24;
}

SCSS

$oxford-by-night: #00192c;
$oxford-by-night-rgb: 0, 25, 44;
$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);
}