#6F6FA6

CSS

:root {
  --twinkle-night: #6f6fa6;
  --twinkle-night-rgb: 111 111 166;
  --twinkle-night-oklch: oklch(0.564 0.084 283.4);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(240 24% 54%);
  border-color: oklch(0.564 0.084 283.4);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6f6fa6;
  --color-twinkle-night-50: #f2f2ff;
  --color-twinkle-night-100: #e4e5ff;
  --color-twinkle-night-200: #d0d0f8;
  --color-twinkle-night-300: #b3b2e2;
  --color-twinkle-night-400: #9798cf;
  --color-twinkle-night-500: #7f7fbd;
  --color-twinkle-night-600: #6b6b9f;
  --color-twinkle-night-700: #565680;
  --color-twinkle-night-800: #3d3f5f;
  --color-twinkle-night-900: #2a2b43;
  --color-twinkle-night-950: #18182b;
}

SCSS

$twinkle-night: #6f6fa6;
$twinkle-night-rgb: 111, 111, 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);
}