#3C709B

CSS

:root {
  --muted-blue: #3c709b;
  --muted-blue-rgb: 60 112 155;
  --muted-blue-oklch: oklch(0.528 0.088 245.5);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(207 44% 42%);
  border-color: oklch(0.528 0.088 245.5);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #3c709b;
  --color-muted-blue-50: #e2f8ff;
  --color-muted-blue-100: #d1ebff;
  --color-muted-blue-200: #b7d8f9;
  --color-muted-blue-300: #94bce3;
  --color-muted-blue-400: #72a4d0;
  --color-muted-blue-500: #518cbd;
  --color-muted-blue-600: #45769f;
  --color-muted-blue-700: #375f80;
  --color-muted-blue-800: #26465f;
  --color-muted-blue-900: #193042;
  --color-muted-blue-950: #091c2b;
}

SCSS

$muted-blue: #3c709b;
$muted-blue-rgb: 60, 112, 155;
$muted-blue-light: mix(#fff, $muted-blue, 20%);
$muted-blue-dark: mix(#000, $muted-blue, 20%);

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