#6970AB

CSS

:root {
  --twinkle-night: #6970ab;
  --twinkle-night-rgb: 105 112 171;
  --twinkle-night-oklch: oklch(0.564 0.091 277.9);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(234 28% 54%);
  border-color: oklch(0.564 0.091 277.9);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6970ab;
  --color-twinkle-night-50: #eff3ff;
  --color-twinkle-night-100: #e1e5ff;
  --color-twinkle-night-200: #ccd1fc;
  --color-twinkle-night-300: #adb3e6;
  --color-twinkle-night-400: #9199d4;
  --color-twinkle-night-500: #7880c2;
  --color-twinkle-night-600: #666ca4;
  --color-twinkle-night-700: #515784;
  --color-twinkle-night-800: #3a3f62;
  --color-twinkle-night-900: #272c45;
  --color-twinkle-night-950: #16192d;
}

SCSS

$twinkle-night: #6970ab;
$twinkle-night-rgb: 105, 112, 171;
$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);
}