#4E78A4

CSS

:root {
  --into-the-blue: #4e78a4;
  --into-the-blue-rgb: 78 120 164;
  --into-the-blue-oklch: oklch(0.561 0.083 250.6);
}

.element {
  color: var(--into-the-blue);
  background-color: hsl(211 36% 47%);
  border-color: oklch(0.561 0.083 250.6);
}

Tailwind CSS v4

@theme {
  --color-into-the-blue: #4e78a4;
  --color-into-the-blue-50: #e5f7ff;
  --color-into-the-blue-100: #d5eaff;
  --color-into-the-blue-200: #bcd7f8;
  --color-into-the-blue-300: #99bbe2;
  --color-into-the-blue-400: #79a2ce;
  --color-into-the-blue-500: #5b8abc;
  --color-into-the-blue-600: #4d759e;
  --color-into-the-blue-700: #3d5d7f;
  --color-into-the-blue-800: #2b455e;
  --color-into-the-blue-900: #1d3042;
  --color-into-the-blue-950: #0d1c2a;
}

SCSS

$into-the-blue: #4e78a4;
$into-the-blue-rgb: 78, 120, 164;
$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);
}