#0A6FBC

CSS

:root {
  --french-blue: #0a6fbc;
  --french-blue-rgb: 10 111 188;
  --french-blue-oklch: oklch(0.532 0.145 249.6);
}

.element {
  color: var(--french-blue);
  background-color: hsl(206 90% 39%);
  border-color: oklch(0.532 0.145 249.6);
}

Tailwind CSS v4

@theme {
  --color-french-blue: #0a6fbc;
  --color-french-blue-50: #d8f9ff;
  --color-french-blue-100: #c5ecff;
  --color-french-blue-200: #a7d9ff;
  --color-french-blue-300: #7ebcff;
  --color-french-blue-400: #53a3f0;
  --color-french-blue-500: #218ae1;
  --color-french-blue-600: #2075be;
  --color-french-blue-700: #195d99;
  --color-french-blue-800: #0a4572;
  --color-french-blue-900: #073050;
  --color-french-blue-950: #001c35;
}

SCSS

$french-blue: #0a6fbc;
$french-blue-rgb: 10, 111, 188;
$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);
}