#5071C4

CSS

:root {
  --serenity-s-reign: #5071c4;
  --serenity-s-reign-rgb: 80 113 196;
  --serenity-s-reign-oklch: oklch(0.564 0.134 265.9);
}

.element {
  color: var(--serenity-s-reign);
  background-color: hsl(223 50% 54%);
  border-color: oklch(0.564 0.134 265.9);
}

Tailwind CSS v4

@theme {
  --color-serenity-s-reign: #5071c4;
  --color-serenity-s-reign-50: #e4f5ff;
  --color-serenity-s-reign-100: #d4e7ff;
  --color-serenity-s-reign-200: #bbd3ff;
  --color-serenity-s-reign-300: #9ab5fd;
  --color-serenity-s-reign-400: #799bee;
  --color-serenity-s-reign-500: #5c81de;
  --color-serenity-s-reign-600: #4e6dbc;
  --color-serenity-s-reign-700: #3e5797;
  --color-serenity-s-reign-800: #2a4070;
  --color-serenity-s-reign-900: #1c2c4f;
  --color-serenity-s-reign-950: #0d1935;
}

SCSS

$serenity-s-reign: #5071c4;
$serenity-s-reign-rgb: 80, 113, 196;
$serenity-s-reign-light: mix(#fff, $serenity-s-reign, 20%);
$serenity-s-reign-dark: mix(#000, $serenity-s-reign, 20%);

.element {
  color: $serenity-s-reign;
  box-shadow: 0 0 0 2px rgba($serenity-s-reign, 0.35);
}