#006EBF

CSS

:root {
  --french-blue: #006ebf;
  --french-blue-rgb: 0 110 191;
  --french-blue-oklch: oklch(0.531 0.151 250.3);
}

.element {
  color: var(--french-blue);
  background-color: hsl(205 100% 37%);
  border-color: oklch(0.531 0.151 250.3);
}

Tailwind CSS v4

@theme {
  --color-french-blue: #006ebf;
  --color-french-blue-50: #d7f9ff;
  --color-french-blue-100: #c4ecff;
  --color-french-blue-200: #a5d9ff;
  --color-french-blue-300: #7dbcff;
  --color-french-blue-400: #51a3f4;
  --color-french-blue-500: #1b89e5;
  --color-french-blue-600: #1b74c1;
  --color-french-blue-700: #165d9b;
  --color-french-blue-800: #074574;
  --color-french-blue-900: #053052;
  --color-french-blue-950: #001c37;
}

SCSS

$french-blue: #006ebf;
$french-blue-rgb: 0, 110, 191;
$french-blue-light: mix(#fff, $french-blue, 20%);
$french-blue-dark: mix(#000, $french-blue, 20%);

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