#4978A5

CSS

:root {
  --into-the-blue: #4978a5;
  --into-the-blue-rgb: 73 120 165;
  --into-the-blue-oklch: oklch(0.559 0.087 248.6);
}

.element {
  color: var(--into-the-blue);
  background-color: hsl(209 39% 47%);
  border-color: oklch(0.559 0.087 248.6);
}

Tailwind CSS v4

@theme {
  --color-into-the-blue: #4978a5;
  --color-into-the-blue-50: #e3f8ff;
  --color-into-the-blue-100: #d3ebff;
  --color-into-the-blue-200: #b9d8f9;
  --color-into-the-blue-300: #96bbe3;
  --color-into-the-blue-400: #75a3d0;
  --color-into-the-blue-500: #568bbd;
  --color-into-the-blue-600: #4975a0;
  --color-into-the-blue-700: #3a5e80;
  --color-into-the-blue-800: #28455f;
  --color-into-the-blue-900: #1b3043;
  --color-into-the-blue-950: #0b1c2b;
}

SCSS

$into-the-blue: #4978a5;
$into-the-blue-rgb: 73, 120, 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);
}