#5E77A3

CSS

:root {
  --montreux-blue: #5e77a3;
  --montreux-blue-rgb: 94 119 163;
  --montreux-blue-oklch: oklch(0.568 0.075 261.4);
}

.element {
  color: var(--montreux-blue);
  background-color: hsl(218 27% 50%);
  border-color: oklch(0.568 0.075 261.4);
}

Tailwind CSS v4

@theme {
  --color-montreux-blue: #5e77a3;
  --color-montreux-blue-50: #eaf6ff;
  --color-montreux-blue-100: #dbe8ff;
  --color-montreux-blue-200: #c4d5f5;
  --color-montreux-blue-300: #a4b8de;
  --color-montreux-blue-400: #869fcb;
  --color-montreux-blue-500: #6a87b8;
  --color-montreux-blue-600: #5a729b;
  --color-montreux-blue-700: #485b7d;
  --color-montreux-blue-800: #33435c;
  --color-montreux-blue-900: #232e41;
  --color-montreux-blue-950: #121b29;
}

SCSS

$montreux-blue: #5e77a3;
$montreux-blue-rgb: 94, 119, 163;
$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);
}