#0070C3

CSS

:root {
  --french-blue: #0070c3;
  --french-blue-rgb: 0 112 195;
  --french-blue-oklch: oklch(0.538 0.154 250.5);
}

.element {
  color: var(--french-blue);
  background-color: hsl(206 100% 38%);
  border-color: oklch(0.538 0.154 250.5);
}

Tailwind CSS v4

@theme {
  --color-french-blue: #0070c3;
  --color-french-blue-50: #d6f9ff;
  --color-french-blue-100: #c4ecff;
  --color-french-blue-200: #a4d9ff;
  --color-french-blue-300: #7cbcff;
  --color-french-blue-400: #4fa3f5;
  --color-french-blue-500: #1789e7;
  --color-french-blue-600: #1974c3;
  --color-french-blue-700: #145d9d;
  --color-french-blue-800: #054575;
  --color-french-blue-900: #042f52;
  --color-french-blue-950: #001b37;
}

SCSS

$french-blue: #0070c3;
$french-blue-rgb: 0, 112, 195;
$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);
}