#1B6FB8

CSS

:root {
  --french-blue: #1b6fb8;
  --french-blue-rgb: 27 111 184;
  --french-blue-oklch: oklch(0.532 0.138 250.1);
}

.element {
  color: var(--french-blue);
  background-color: hsl(208 74% 41%);
  border-color: oklch(0.532 0.138 250.1);
}

Tailwind CSS v4

@theme {
  --color-french-blue: #1b6fb8;
  --color-french-blue-50: #d9f9ff;
  --color-french-blue-100: #c7ecff;
  --color-french-blue-200: #aad9ff;
  --color-french-blue-300: #83bcfc;
  --color-french-blue-400: #5aa3ec;
  --color-french-blue-500: #2e8add;
  --color-french-blue-600: #2975ba;
  --color-french-blue-700: #215d96;
  --color-french-blue-800: #12456f;
  --color-french-blue-900: #0b304e;
  --color-french-blue-950: #001c34;
}

SCSS

$french-blue: #1b6fb8;
$french-blue-rgb: 27, 111, 184;
$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);
}