#1D6EBB

CSS

:root {
  --matt-blue: #1d6ebb;
  --matt-blue-rgb: 29 110 187;
  --matt-blue-oklch: oklch(0.532 0.142 251.8);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(209 73% 42%);
  border-color: oklch(0.532 0.142 251.8);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #1d6ebb;
  --color-matt-blue-50: #daf8ff;
  --color-matt-blue-100: #c8ebff;
  --color-matt-blue-200: #aad8ff;
  --color-matt-blue-300: #83bbff;
  --color-matt-blue-400: #5ba2ef;
  --color-matt-blue-500: #3089e0;
  --color-matt-blue-600: #2b74bd;
  --color-matt-blue-700: #225d98;
  --color-matt-blue-800: #124471;
  --color-matt-blue-900: #0c2f50;
  --color-matt-blue-950: #011b35;
}

SCSS

$matt-blue: #1d6ebb;
$matt-blue-rgb: 29, 110, 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);
}