#1B6FB7

CSS

:root {
  --french-blue: #1b6fb7;
  --french-blue-rgb: 27 111 183;
  --french-blue-oklch: oklch(0.531 0.136 249.8);
}

.element {
  color: var(--french-blue);
  background-color: hsl(208 74% 41%);
  border-color: oklch(0.531 0.136 249.8);
}

Tailwind CSS v4

@theme {
  --color-french-blue: #1b6fb7;
  --color-french-blue-50: #daf9ff;
  --color-french-blue-100: #c7ecff;
  --color-french-blue-200: #aad9ff;
  --color-french-blue-300: #83bcfb;
  --color-french-blue-400: #5aa3eb;
  --color-french-blue-500: #2f8adc;
  --color-french-blue-600: #2a75b9;
  --color-french-blue-700: #215e95;
  --color-french-blue-800: #12456f;
  --color-french-blue-900: #0b304e;
  --color-french-blue-950: #011c34;
}

SCSS

$french-blue: #1b6fb7;
$french-blue-rgb: 27, 111, 183;
$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);
}