#6972A1

CSS

:root {
  --twinkle-night: #6972a1;
  --twinkle-night-rgb: 105 114 161;
  --twinkle-night-oklch: oklch(0.564 0.074 275.4);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(230 23% 52%);
  border-color: oklch(0.564 0.074 275.4);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6972a1;
  --color-twinkle-night-50: #eff4ff;
  --color-twinkle-night-100: #e1e6ff;
  --color-twinkle-night-200: #ccd2f4;
  --color-twinkle-night-300: #aeb5de;
  --color-twinkle-night-400: #929bca;
  --color-twinkle-night-500: #7882b7;
  --color-twinkle-night-600: #666e9b;
  --color-twinkle-night-700: #51587c;
  --color-twinkle-night-800: #3a415c;
  --color-twinkle-night-900: #282d40;
  --color-twinkle-night-950: #161a29;
}

SCSS

$twinkle-night: #6972a1;
$twinkle-night-rgb: 105, 114, 161;
$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);
}