#001A2A

CSS

:root {
  --oxford-by-night: #001a2a;
  --oxford-by-night-rgb: 0 26 42;
  --oxford-by-night-oklch: oklch(0.207 0.046 238.3);
}

.element {
  color: var(--oxford-by-night);
  background-color: hsl(203 100% 8%);
  border-color: oklch(0.207 0.046 238.3);
}

Tailwind CSS v4

@theme {
  --color-oxford-by-night: #001a2a;
  --color-oxford-by-night-50: #eaf7ff;
  --color-oxford-by-night-100: #dbeaf6;
  --color-oxford-by-night-200: #c3d7e6;
  --color-oxford-by-night-300: #a3bbcd;
  --color-oxford-by-night-400: #86a3b7;
  --color-oxford-by-night-500: #6a8ba2;
  --color-oxford-by-night-600: #5a7689;
  --color-oxford-by-night-700: #485e6d;
  --color-oxford-by-night-800: #334550;
  --color-oxford-by-night-900: #233038;
  --color-oxford-by-night-950: #121c23;
}

SCSS

$oxford-by-night: #001a2a;
$oxford-by-night-rgb: 0, 26, 42;
$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);
}