#6874A6

CSS

:root {
  --twinkle-night: #6874a6;
  --twinkle-night-rgb: 104 116 166;
  --twinkle-night-oklch: oklch(0.57 0.079 273.3);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(228 26% 53%);
  border-color: oklch(0.57 0.079 273.3);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6874a6;
  --color-twinkle-night-50: #eef4ff;
  --color-twinkle-night-100: #e0e6ff;
  --color-twinkle-night-200: #cad2f7;
  --color-twinkle-night-300: #abb5e0;
  --color-twinkle-night-400: #8f9cce;
  --color-twinkle-night-500: #7583bb;
  --color-twinkle-night-600: #636f9e;
  --color-twinkle-night-700: #4f587e;
  --color-twinkle-night-800: #38415e;
  --color-twinkle-night-900: #272d42;
  --color-twinkle-night-950: #151a2a;
}

SCSS

$twinkle-night: #6874a6;
$twinkle-night-rgb: 104, 116, 166;
$twinkle-night-light: mix(#fff, $twinkle-night, 20%);
$twinkle-night-dark: mix(#000, $twinkle-night, 20%);

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