#01192B

CSS

:root {
  --oxford-by-night: #01192b;
  --oxford-by-night-rgb: 1 25 43;
  --oxford-by-night-oklch: oklch(0.205 0.048 243.1);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(206 95% 9%);
  border-color: oklch(0.205 0.048 243.1);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #01192b;
  --color-oxford-by-night-50: #eaf7ff;
  --color-oxford-by-night-100: #dbeaf7;
  --color-oxford-by-night-200: #c4d7e8;
  --color-oxford-by-night-300: #a4bbcf;
  --color-oxford-by-night-400: #87a2b9;
  --color-oxford-by-night-500: #6b8aa4;
  --color-oxford-by-night-600: #5b758a;
  --color-oxford-by-night-700: #485e6f;
  --color-oxford-by-night-800: #344552;
  --color-oxford-by-night-900: #233039;
  --color-oxford-by-night-950: #121c23;
}

SCSS

$oxford-by-night: #01192b;
$oxford-by-night-rgb: 1, 25, 43;
$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);
}