#006FD8

CSS

:root {
  --matt-blue: #006fd8;
  --matt-blue-rgb: 0 111 216;
  --matt-blue-oklch: oklch(0.55 0.182 255.1);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(209 100% 42%);
  border-color: oklch(0.55 0.182 255.1);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #006fd8;
  --color-matt-blue-50: #d5f8ff;
  --color-matt-blue-100: #c2ebff;
  --color-matt-blue-200: #a2d7ff;
  --color-matt-blue-300: #79b9ff;
  --color-matt-blue-400: #4b9fff;
  --color-matt-blue-500: #0d83fa;
  --color-matt-blue-600: #1270d3;
  --color-matt-blue-700: #0f59aa;
  --color-matt-blue-800: #00427f;
  --color-matt-blue-900: #012e59;
  --color-matt-blue-950: #001a3d;
}

SCSS

$matt-blue: #006fd8;
$matt-blue-rgb: 0, 111, 216;
$matt-blue-light: mix(#fff, $matt-blue, 20%);
$matt-blue-dark: mix(#000, $matt-blue, 20%);

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