#5D789E

CSS

:root {
  --montreux-blue: #5d789e;
  --montreux-blue-rgb: 93 120 158;
  --montreux-blue-oklch: oklch(0.567 0.067 257);
}

.element {
  color: var(--montreux-blue);
  background-color: hsl(215 26% 49%);
  border-color: oklch(0.567 0.067 257);
}

Tailwind CSS v4

@theme {
  --color-montreux-blue: #5d789e;
  --color-montreux-blue-50: #eaf6ff;
  --color-montreux-blue-100: #dbe9ff;
  --color-montreux-blue-200: #c3d6f2;
  --color-montreux-blue-300: #a3b9da;
  --color-montreux-blue-400: #85a0c6;
  --color-montreux-blue-500: #6a88b3;
  --color-montreux-blue-600: #5a7397;
  --color-montreux-blue-700: #475c79;
  --color-montreux-blue-800: #334459;
  --color-montreux-blue-900: #222f3f;
  --color-montreux-blue-950: #111b28;
}

SCSS

$montreux-blue: #5d789e;
$montreux-blue-rgb: 93, 120, 158;
$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);
}