#5179A5

CSS

:root {
  --into-the-blue: #5179a5;
  --into-the-blue-rgb: 81 121 165;
  --into-the-blue-oklch: oklch(0.565 0.082 251.7);
}

.element {
  color: var(--into-the-blue);
  background-color: hsl(211 34% 48%);
  border-color: oklch(0.565 0.082 251.7);
}

Tailwind CSS v4

@theme {
  --color-into-the-blue: #5179a5;
  --color-into-the-blue-50: #e5f7ff;
  --color-into-the-blue-100: #d5eaff;
  --color-into-the-blue-200: #bcd7f7;
  --color-into-the-blue-300: #9bbae1;
  --color-into-the-blue-400: #7ba2ce;
  --color-into-the-blue-500: #5d8abb;
  --color-into-the-blue-600: #4f749e;
  --color-into-the-blue-700: #3f5d7f;
  --color-into-the-blue-800: #2c455e;
  --color-into-the-blue-900: #1d2f42;
  --color-into-the-blue-950: #0d1c2a;
}

SCSS

$into-the-blue: #5179a5;
$into-the-blue-rgb: 81, 121, 165;
$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);
}