#6D70A4

CSS

:root {
  --twinkle-night: #6d70a4;
  --twinkle-night-rgb: 109 112 164;
  --twinkle-night-oklch: oklch(0.564 0.08 281);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(237 23% 54%);
  border-color: oklch(0.564 0.08 281);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6d70a4;
  --color-twinkle-night-50: #f1f3ff;
  --color-twinkle-night-100: #e3e5ff;
  --color-twinkle-night-200: #cfd1f6;
  --color-twinkle-night-300: #b1b3e0;
  --color-twinkle-night-400: #9599cd;
  --color-twinkle-night-500: #7c80ba;
  --color-twinkle-night-600: #696c9d;
  --color-twinkle-night-700: #54577e;
  --color-twinkle-night-800: #3c3f5e;
  --color-twinkle-night-900: #292c42;
  --color-twinkle-night-950: #17192a;
}

SCSS

$twinkle-night: #6d70a4;
$twinkle-night-rgb: 109, 112, 164;
$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);
}