#5279A7

CSS

:root {
  --montreux-blue: #5279a7;
  --montreux-blue-rgb: 82 121 167;
  --montreux-blue-oklch: oklch(0.567 0.084 253.3);
}

.element {
  color: var(--montreux-blue);
  background-color: hsl(212 34% 49%);
  border-color: oklch(0.567 0.084 253.3);
}

Tailwind CSS v4

@theme {
  --color-montreux-blue: #5279a7;
  --color-montreux-blue-50: #e6f7ff;
  --color-montreux-blue-100: #d6eaff;
  --color-montreux-blue-200: #bdd7f8;
  --color-montreux-blue-300: #9bbae2;
  --color-montreux-blue-400: #7ba2cf;
  --color-montreux-blue-500: #5d89bd;
  --color-montreux-blue-600: #4f749f;
  --color-montreux-blue-700: #3f5d80;
  --color-montreux-blue-800: #2c445f;
  --color-montreux-blue-900: #1e2f42;
  --color-montreux-blue-950: #0d1c2b;
}

SCSS

$montreux-blue: #5279a7;
$montreux-blue-rgb: 82, 121, 167;
$montreux-blue-light: mix(#fff, $montreux-blue, 20%);
$montreux-blue-dark: mix(#000, $montreux-blue, 20%);

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