#3E709E

CSS

:root {
  --muted-blue: #3e709e;
  --muted-blue-rgb: 62 112 158;
  --muted-blue-oklch: oklch(0.531 0.091 248);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(209 44% 43%);
  border-color: oklch(0.531 0.091 248);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #3e709e;
  --color-muted-blue-50: #e2f8ff;
  --color-muted-blue-100: #d2ebff;
  --color-muted-blue-200: #b8d8fa;
  --color-muted-blue-300: #94bce5;
  --color-muted-blue-400: #73a3d2;
  --color-muted-blue-500: #528bbf;
  --color-muted-blue-600: #4676a2;
  --color-muted-blue-700: #385e82;
  --color-muted-blue-800: #264560;
  --color-muted-blue-900: #193043;
  --color-muted-blue-950: #0a1c2b;
}

SCSS

$muted-blue: #3e709e;
$muted-blue-rgb: 62, 112, 158;
$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);
}