#1B3AA2

CSS

:root {
  --blue-hour: #1b3aa2;
  --blue-hour-rgb: 27 58 162;
  --blue-hour-oklch: oklch(0.4 0.172 265.8);
}

.element {
  color: var(--blue-hour);
  background-color: hsl(226 71% 37%);
  border-color: oklch(0.4 0.172 265.8);
}

Tailwind CSS v4

@theme {
  --color-blue-hour: #1b3aa2;
  --color-blue-hour-50: #e0f4ff;
  --color-blue-hour-100: #cfe7ff;
  --color-blue-hour-200: #b4d2ff;
  --color-blue-hour-300: #91b3ff;
  --color-blue-hour-400: #6e99ff;
  --color-blue-hour-500: #4f7df6;
  --color-blue-hour-600: #446ad0;
  --color-blue-hour-700: #3655a7;
  --color-blue-hour-800: #223e7d;
  --color-blue-hour-900: #172b58;
  --color-blue-hour-950: #08183c;
}

SCSS

$blue-hour: #1b3aa2;
$blue-hour-rgb: 27, 58, 162;
$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);
}