#3F9FF6

CSS

:root {
  --fresh-blue-of-bel-air: #3f9ff6;
  --fresh-blue-of-bel-air-rgb: 63 159 246;
  --fresh-blue-of-bel-air-oklch: oklch(0.687 0.156 249.4);
}

.element {
  color: var(--fresh-blue-of-bel-air);
  background-color: hsl(209 91% 61%);
  border-color: oklch(0.687 0.156 249.4);
}

Tailwind CSS v4

@theme {
  --color-fresh-blue-of-bel-air: #3f9ff6;
  --color-fresh-blue-of-bel-air-50: #d5f9ff;
  --color-fresh-blue-of-bel-air-100: #c2ecff;
  --color-fresh-blue-of-bel-air-200: #a2d9ff;
  --color-fresh-blue-of-bel-air-300: #79bcff;
  --color-fresh-blue-of-bel-air-400: #4ba3f6;
  --color-fresh-blue-of-bel-air-500: #0389e8;
  --color-fresh-blue-of-bel-air-600: #0d74c4;
  --color-fresh-blue-of-bel-air-700: #0c5d9d;
  --color-fresh-blue-of-bel-air-800: #004575;
  --color-fresh-blue-of-bel-air-900: #013052;
  --color-fresh-blue-of-bel-air-950: #001c37;
}

SCSS

$fresh-blue-of-bel-air: #3f9ff6;
$fresh-blue-of-bel-air-rgb: 63, 159, 246;
$fresh-blue-of-bel-air-light: mix(#fff, $fresh-blue-of-bel-air, 20%);
$fresh-blue-of-bel-air-dark: mix(#000, $fresh-blue-of-bel-air, 20%);

.element {
  color: $fresh-blue-of-bel-air;
  box-shadow: 0 0 0 2px rgba($fresh-blue-of-bel-air, 0.35);
}