#3870A0

CSS

:root {
  --muted-blue: #3870a0;
  --muted-blue-rgb: 56 112 160;
  --muted-blue-oklch: oklch(0.529 0.096 246.8);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(208 48% 42%);
  border-color: oklch(0.529 0.096 246.8);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #3870a0;
  --color-muted-blue-50: #e1f8ff;
  --color-muted-blue-100: #d0ebff;
  --color-muted-blue-200: #b5d8fc;
  --color-muted-blue-300: #91bce7;
  --color-muted-blue-400: #6ea4d4;
  --color-muted-blue-500: #4c8cc2;
  --color-muted-blue-600: #4276a4;
  --color-muted-blue-700: #345f84;
  --color-muted-blue-800: #234661;
  --color-muted-blue-900: #173044;
  --color-muted-blue-950: #081c2c;
}

SCSS

$muted-blue: #3870a0;
$muted-blue-rgb: 56, 112, 160;
$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);
}