#3471A0

CSS

:root {
  --muted-blue: #3471a0;
  --muted-blue-rgb: 52 113 160;
  --muted-blue-oklch: oklch(0.53 0.097 244.5);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(206 51% 42%);
  border-color: oklch(0.53 0.097 244.5);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #3471a0;
  --color-muted-blue-50: #dff9ff;
  --color-muted-blue-100: #ceecff;
  --color-muted-blue-200: #b3d9fc;
  --color-muted-blue-300: #8fbde7;
  --color-muted-blue-400: #6ba5d4;
  --color-muted-blue-500: #488cc2;
  --color-muted-blue-600: #3e77a4;
  --color-muted-blue-700: #315f83;
  --color-muted-blue-800: #214661;
  --color-muted-blue-900: #163144;
  --color-muted-blue-950: #071d2c;
}

SCSS

$muted-blue: #3471a0;
$muted-blue-rgb: 52, 113, 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);
}