#156DC4

CSS

:root {
  --matt-blue: #156dc4;
  --matt-blue-rgb: 21 109 196;
  --matt-blue-oklch: oklch(0.534 0.156 253.4);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(210 81% 43%);
  border-color: oklch(0.534 0.156 253.4);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #156dc4;
  --color-matt-blue-50: #d8f8ff;
  --color-matt-blue-100: #c6ebff;
  --color-matt-blue-200: #a7d8ff;
  --color-matt-blue-300: #80baff;
  --color-matt-blue-400: #56a1f8;
  --color-matt-blue-500: #2887ea;
  --color-matt-blue-600: #2472c5;
  --color-matt-blue-700: #1d5c9e;
  --color-matt-blue-800: #0d4476;
  --color-matt-blue-900: #082f53;
  --color-matt-blue-950: #001b38;
}

SCSS

$matt-blue: #156dc4;
$matt-blue-rgb: 21, 109, 196;
$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);
}