#2A6DBB

CSS

:root {
  --matt-blue: #2a6dbb;
  --matt-blue-rgb: 42 109 187;
  --matt-blue-oklch: oklch(0.533 0.14 254.6);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(212 63% 45%);
  border-color: oklch(0.533 0.14 254.6);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #2a6dbb;
  --color-matt-blue-50: #dcf8ff;
  --color-matt-blue-100: #caeaff;
  --color-matt-blue-200: #aed7ff;
  --color-matt-blue-300: #88bafe;
  --color-matt-blue-400: #62a1ef;
  --color-matt-blue-500: #3c87e0;
  --color-matt-blue-600: #3472bd;
  --color-matt-blue-700: #295c98;
  --color-matt-blue-800: #194471;
  --color-matt-blue-900: #102f50;
  --color-matt-blue-950: #031b35;
}

SCSS

$matt-blue: #2a6dbb;
$matt-blue-rgb: 42, 109, 187;
$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);
}