#6771AD

CSS

:root {
  --twinkle-night: #6771ad;
  --twinkle-night-rgb: 103 113 173;
  --twinkle-night-oklch: oklch(0.566 0.094 275.8);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(231 30% 54%);
  border-color: oklch(0.566 0.094 275.8);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6771ad;
  --color-twinkle-night-50: #eef3ff;
  --color-twinkle-night-100: #e0e6ff;
  --color-twinkle-night-200: #cad1fd;
  --color-twinkle-night-300: #abb3e7;
  --color-twinkle-night-400: #8f9ad6;
  --color-twinkle-night-500: #7580c4;
  --color-twinkle-night-600: #636da5;
  --color-twinkle-night-700: #4f5785;
  --color-twinkle-night-800: #384063;
  --color-twinkle-night-900: #262c45;
  --color-twinkle-night-950: #15192d;
}

SCSS

$twinkle-night: #6771ad;
$twinkle-night-rgb: 103, 113, 173;
$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);
}