#0F6CC9

CSS

:root {
  --matt-blue: #0f6cc9;
  --matt-blue-rgb: 15 108 201;
  --matt-blue-oklch: oklch(0.535 0.165 254.3);
}

.element {
  color: var(--matt-blue);
  background-color: hsl(210 86% 42%);
  border-color: oklch(0.535 0.165 254.3);
}

Tailwind CSS v4

@theme {
  --color-matt-blue: #0f6cc9;
  --color-matt-blue-50: #d7f8ff;
  --color-matt-blue-100: #c5ebff;
  --color-matt-blue-200: #a6d7ff;
  --color-matt-blue-300: #7ebaff;
  --color-matt-blue-400: #53a0fd;
  --color-matt-blue-500: #2386ef;
  --color-matt-blue-600: #2171ca;
  --color-matt-blue-700: #1a5ba2;
  --color-matt-blue-800: #094379;
  --color-matt-blue-900: #062e55;
  --color-matt-blue-950: #001a3a;
}

SCSS

$matt-blue: #0f6cc9;
$matt-blue-rgb: 15, 108, 201;
$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);
}