#004262

CSS

:root {
  --capital-blue: #004262;
  --capital-blue-rgb: 0 66 98;
  --capital-blue-oklch: oklch(0.36 0.08 238.3);
}

.element {
  color: var(--capital-blue);
  background-color: hsl(200 100% 19%);
  border-color: oklch(0.36 0.08 238.3);
}

Tailwind CSS v4

@theme {
  --color-capital-blue: #004262;
  --color-capital-blue-50: #e1f9ff;
  --color-capital-blue-100: #d1ecff;
  --color-capital-blue-200: #b6daf4;
  --color-capital-blue-300: #92bddd;
  --color-capital-blue-400: #71a6c9;
  --color-capital-blue-500: #4f8eb5;
  --color-capital-blue-600: #447899;
  --color-capital-blue-700: #36607b;
  --color-capital-blue-800: #25475b;
  --color-capital-blue-900: #19313f;
  --color-capital-blue-950: #091d28;
}

SCSS

$capital-blue: #004262;
$capital-blue-rgb: 0, 66, 98;
$capital-blue-light: mix(#fff, $capital-blue, 20%);
$capital-blue-dark: mix(#000, $capital-blue, 20%);

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