#5179A7

CSS

:root {
  --into-the-blue: #5179a7;
  --into-the-blue-rgb: 81 121 167;
  --into-the-blue-oklch: oklch(0.566 0.085 252.7);
}

.element {
  color: var(--into-the-blue);
  background-color: hsl(212 35% 49%);
  border-color: oklch(0.566 0.085 252.7);
}

Tailwind CSS v4

@theme {
  --color-into-the-blue: #5179a7;
  --color-into-the-blue-50: #e5f7ff;
  --color-into-the-blue-100: #d5eaff;
  --color-into-the-blue-200: #bcd7f9;
  --color-into-the-blue-300: #9abae3;
  --color-into-the-blue-400: #7aa2d0;
  --color-into-the-blue-500: #5c89bd;
  --color-into-the-blue-600: #4f74a0;
  --color-into-the-blue-700: #3f5d80;
  --color-into-the-blue-800: #2b445f;
  --color-into-the-blue-900: #1d2f42;
  --color-into-the-blue-950: #0d1c2b;
}

SCSS

$into-the-blue: #5179a7;
$into-the-blue-rgb: 81, 121, 167;
$into-the-blue-light: mix(#fff, $into-the-blue, 20%);
$into-the-blue-dark: mix(#000, $into-the-blue, 20%);

.element {
  color: $into-the-blue;
  box-shadow: 0 0 0 2px rgba($into-the-blue, 0.35);
}