#1B6FB9

CSS

:root {
  --matt-blue: #1b6fb9;
  --matt-blue-rgb: 27 111 185;
  --matt-blue-oklch: oklch(0.533 0.139 250.4);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(208 75% 42%);
  border-color: oklch(0.533 0.139 250.4);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #1b6fb9;
  --color-matt-blue-50: #d9f9ff;
  --color-matt-blue-100: #c7ecff;
  --color-matt-blue-200: #aad9ff;
  --color-matt-blue-300: #82bcfd;
  --color-matt-blue-400: #5aa3ed;
  --color-matt-blue-500: #2e89de;
  --color-matt-blue-600: #2974bb;
  --color-matt-blue-700: #215d96;
  --color-matt-blue-800: #114570;
  --color-matt-blue-900: #0b304f;
  --color-matt-blue-950: #001c34;
}

SCSS

$matt-blue: #1b6fb9;
$matt-blue-rgb: 27, 111, 185;
$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);
}