#0039A5

CSS

:root {
  --blue-hour: #0039a5;
  --blue-hour-rgb: 0 57 165;
  --blue-hour-oklch: oklch(0.395 0.181 261.9);
}

.element {
  color: var(--blue-hour);
  background-color: hsl(219 100% 32%);
  border-color: oklch(0.395 0.181 261.9);
}

Tailwind CSS v4

@theme {
  --color-blue-hour: #0039a5;
  --color-blue-hour-50: #dbf6ff;
  --color-blue-hour-100: #c9e8ff;
  --color-blue-hour-200: #add4ff;
  --color-blue-hour-300: #87b5ff;
  --color-blue-hour-400: #619bff;
  --color-blue-hour-500: #3d7efc;
  --color-blue-hour-600: #356bd4;
  --color-blue-hour-700: #2a56ab;
  --color-blue-hour-800: #183f80;
  --color-blue-hour-900: #0f2c5a;
  --color-blue-hour-950: #03183d;
}

SCSS

$blue-hour: #0039a5;
$blue-hour-rgb: 0, 57, 165;
$blue-hour-light: mix(#fff, $blue-hour, 20%);
$blue-hour-dark: mix(#000, $blue-hour, 20%);

.element {
  color: $blue-hour;
  box-shadow: 0 0 0 2px rgba($blue-hour, 0.35);
}