#266CC1

CSS

:root {
  --matt-blue: #266cc1;
  --matt-blue-rgb: 38 108 193;
  --matt-blue-oklch: oklch(0.534 0.15 255.6);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(213 67% 45%);
  border-color: oklch(0.534 0.15 255.6);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #266cc1;
  --color-matt-blue-50: #dbf7ff;
  --color-matt-blue-100: #c9eaff;
  --color-matt-blue-200: #acd7ff;
  --color-matt-blue-300: #86b9ff;
  --color-matt-blue-400: #5fa0f5;
  --color-matt-blue-500: #3886e6;
  --color-matt-blue-600: #3171c2;
  --color-matt-blue-700: #275b9c;
  --color-matt-blue-800: #164374;
  --color-matt-blue-900: #0e2e52;
  --color-matt-blue-950: #021b37;
}

SCSS

$matt-blue: #266cc1;
$matt-blue-rgb: 38, 108, 193;
$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);
}