#35719F

CSS

:root {
  --muted-blue: #35719f;
  --muted-blue-rgb: 53 113 159;
  --muted-blue-oklch: oklch(0.53 0.096 244.2);
}

.element {
  color: var(--muted-blue);
  background-color: hsl(206 50% 42%);
  border-color: oklch(0.53 0.096 244.2);
}

Tailwind CSS v4

@theme {
  --color-muted-blue: #35719f;
  --color-muted-blue-50: #e0f9ff;
  --color-muted-blue-100: #cfecff;
  --color-muted-blue-200: #b4d9fb;
  --color-muted-blue-300: #8fbde6;
  --color-muted-blue-400: #6ca5d3;
  --color-muted-blue-500: #498cc1;
  --color-muted-blue-600: #3f77a3;
  --color-muted-blue-700: #325f83;
  --color-muted-blue-800: #214661;
  --color-muted-blue-900: #163144;
  --color-muted-blue-950: #071d2c;
}

SCSS

$muted-blue: #35719f;
$muted-blue-rgb: 53, 113, 159;
$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);
}