#2971A8

CSS

:root {
  --muted-blue: #2971a8;
  --muted-blue-rgb: 41 113 168;
  --muted-blue-oklch: oklch(0.531 0.112 245.5);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(206 61% 41%);
  border-color: oklch(0.531 0.112 245.5);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #2971a8;
  --color-muted-blue-50: #ddf9ff;
  --color-muted-blue-100: #cbecff;
  --color-muted-blue-200: #afd9ff;
  --color-muted-blue-300: #89bdee;
  --color-muted-blue-400: #63a5dc;
  --color-muted-blue-500: #3c8ccb;
  --color-muted-blue-600: #3577ab;
  --color-muted-blue-700: #2a5f8a;
  --color-muted-blue-800: #1a4666;
  --color-muted-blue-900: #113148;
  --color-muted-blue-950: #041d2f;
}

SCSS

$muted-blue: #2971a8;
$muted-blue-rgb: 41, 113, 168;
$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);
}