#3070A4

CSS

:root {
  --muted-blue: #3070a4;
  --muted-blue-rgb: 48 112 164;
  --muted-blue-oklch: oklch(0.528 0.105 246.2);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(207 55% 42%);
  border-color: oklch(0.528 0.105 246.2);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #3070a4;
  --color-muted-blue-50: #def9ff;
  --color-muted-blue-100: #cdecff;
  --color-muted-blue-200: #b2d9ff;
  --color-muted-blue-300: #8dbdeb;
  --color-muted-blue-400: #68a4d9;
  --color-muted-blue-500: #448cc7;
  --color-muted-blue-600: #3b76a8;
  --color-muted-blue-700: #2f5f87;
  --color-muted-blue-800: #1f4664;
  --color-muted-blue-900: #143046;
  --color-muted-blue-950: #061c2e;
}

SCSS

$muted-blue: #3070a4;
$muted-blue-rgb: 48, 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);
}