#346DB4

CSS

:root {
  --matt-blue: #346db4;
  --matt-blue-rgb: 52 109 180;
  --matt-blue-oklch: oklch(0.532 0.127 255.3);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(213 55% 45%);
  border-color: oklch(0.532 0.127 255.3);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #346db4;
  --color-matt-blue-50: #dff7ff;
  --color-matt-blue-100: #ceeaff;
  --color-matt-blue-200: #b2d7ff;
  --color-matt-blue-300: #8ebaf8;
  --color-matt-blue-400: #69a1e8;
  --color-matt-blue-500: #4787d8;
  --color-matt-blue-600: #3d73b6;
  --color-matt-blue-700: #305c93;
  --color-matt-blue-800: #1f446d;
  --color-matt-blue-900: #142f4d;
  --color-matt-blue-950: #061b33;
}

SCSS

$matt-blue: #346db4;
$matt-blue-rgb: 52, 109, 180;
$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);
}