#0F568B

CSS

:root {
  --dark-denim: #0f568b;
  --dark-denim-rgb: 15 86 139;
  --dark-denim-oklch: oklch(0.441 0.109 247.3);
}

.element {
  color: var(--dark-denim);
  background-color: hsl(206 81% 30%);
  border-color: oklch(0.441 0.109 247.3);
}

Tailwind CSS v4

@theme {
  --color-dark-denim: #0f568b;
  --color-dark-denim-50: #def9ff;
  --color-dark-denim-100: #cdecff;
  --color-dark-denim-200: #b1d9ff;
  --color-dark-denim-300: #8cbced;
  --color-dark-denim-400: #67a4db;
  --color-dark-denim-500: #438bca;
  --color-dark-denim-600: #3a76ab;
  --color-dark-denim-700: #2e5f89;
  --color-dark-denim-800: #1e4665;
  --color-dark-denim-900: #133047;
  --color-dark-denim-950: #051c2f;
}

SCSS

$dark-denim: #0f568b;
$dark-denim-rgb: 15, 86, 139;
$dark-denim-light: mix(#fff, $dark-denim, 20%);
$dark-denim-dark: mix(#000, $dark-denim, 20%);

.element {
  color: $dark-denim;
  box-shadow: 0 0 0 2px rgba($dark-denim, 0.35);
}