#2A6FB0

CSS

:root {
  --matt-blue: #2a6fb0;
  --matt-blue-rgb: 42 111 176;
  --matt-blue-oklch: oklch(0.531 0.123 250.3);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(209 61% 43%);
  border-color: oklch(0.531 0.123 250.3);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #2a6fb0;
  --color-matt-blue-50: #ddf8ff;
  --color-matt-blue-100: #cbebff;
  --color-matt-blue-200: #afd8ff;
  --color-matt-blue-300: #89bcf5;
  --color-matt-blue-400: #63a3e4;
  --color-matt-blue-500: #3d8ad4;
  --color-matt-blue-600: #3575b3;
  --color-matt-blue-700: #2a5e90;
  --color-matt-blue-800: #1a456b;
  --color-matt-blue-900: #11304b;
  --color-matt-blue-950: #041c31;
}

SCSS

$matt-blue: #2a6fb0;
$matt-blue-rgb: 42, 111, 176;
$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);
}