#6974A5

CSS

:root {
  --twinkle-night: #6974a5;
  --twinkle-night-rgb: 105 116 165;
  --twinkle-night-oklch: oklch(0.57 0.077 274);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(229 25% 53%);
  border-color: oklch(0.57 0.077 274);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6974a5;
  --color-twinkle-night-50: #eff4ff;
  --color-twinkle-night-100: #e0e6ff;
  --color-twinkle-night-200: #cbd2f6;
  --color-twinkle-night-300: #acb5df;
  --color-twinkle-night-400: #909ccc;
  --color-twinkle-night-500: #7682b9;
  --color-twinkle-night-600: #646e9d;
  --color-twinkle-night-700: #50587e;
  --color-twinkle-night-800: #39415d;
  --color-twinkle-night-900: #272d41;
  --color-twinkle-night-950: #151a2a;
}

SCSS

$twinkle-night: #6974a5;
$twinkle-night-rgb: 105, 116, 165;
$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);
}