#1A70B4

CSS

:root {
  --french-blue: #1a70b4;
  --french-blue-rgb: 26 112 180;
  --french-blue-oklch: oklch(0.532 0.132 248.2);
}

.element {
  color: var(--french-blue);
  background-color: hsl(206 75% 40%);
  border-color: oklch(0.532 0.132 248.2);
}

Tailwind CSS v4

@theme {
  --color-french-blue: #1a70b4;
  --color-french-blue-50: #daf9ff;
  --color-french-blue-100: #c7ecff;
  --color-french-blue-200: #aad9ff;
  --color-french-blue-300: #83bcf9;
  --color-french-blue-400: #5aa4e8;
  --color-french-blue-500: #2e8bd8;
  --color-french-blue-600: #2976b6;
  --color-french-blue-700: #215e93;
  --color-french-blue-800: #12456d;
  --color-french-blue-900: #0b304d;
  --color-french-blue-950: #001c33;
}

SCSS

$french-blue: #1a70b4;
$french-blue-rgb: 26, 112, 180;
$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);
}