#5E789F

CSS

:root {
  --montreux-blue: #5e789f;
  --montreux-blue-rgb: 94 120 159;
  --montreux-blue-oklch: oklch(0.568 0.068 258.3);
}

.element {
  color: var(--montreux-blue);
  background-color: hsl(216 26% 50%);
  border-color: oklch(0.568 0.068 258.3);
}

Tailwind CSS v4

@theme {
  --color-montreux-blue: #5e789f;
  --color-montreux-blue-50: #eaf6ff;
  --color-montreux-blue-100: #dbe9ff;
  --color-montreux-blue-200: #c4d5f2;
  --color-montreux-blue-300: #a4b9db;
  --color-montreux-blue-400: #86a0c7;
  --color-montreux-blue-500: #6a88b3;
  --color-montreux-blue-600: #5a7397;
  --color-montreux-blue-700: #485c7a;
  --color-montreux-blue-800: #33435a;
  --color-montreux-blue-900: #232f3f;
  --color-montreux-blue-950: #121b28;
}

SCSS

$montreux-blue: #5e789f;
$montreux-blue-rgb: 94, 120, 159;
$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);
}