#3470A4

CSS

:root {
  --muted-blue: #3470a4;
  --muted-blue-rgb: 52 112 164;
  --muted-blue-oklch: oklch(0.53 0.103 247.4);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(208 52% 42%);
  border-color: oklch(0.53 0.103 247.4);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #3470a4;
  --color-muted-blue-50: #dff8ff;
  --color-muted-blue-100: #ceebff;
  --color-muted-blue-200: #b3d9ff;
  --color-muted-blue-300: #8fbceb;
  --color-muted-blue-400: #6ba4d8;
  --color-muted-blue-500: #488bc7;
  --color-muted-blue-600: #3e76a8;
  --color-muted-blue-700: #315e87;
  --color-muted-blue-800: #204664;
  --color-muted-blue-900: #153046;
  --color-muted-blue-950: #071c2e;
}

SCSS

$muted-blue: #3470a4;
$muted-blue-rgb: 52, 112, 164;
$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);
}