#5F699E

CSS

:root {
  --twinkle-night: #5f699e;
  --twinkle-night-rgb: 95 105 158;
  --twinkle-night-oklch: oklch(0.535 0.084 275);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(230 25% 50%);
  border-color: oklch(0.535 0.084 275);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #5f699e;
  --color-twinkle-night-50: #eff4ff;
  --color-twinkle-night-100: #e0e6ff;
  --color-twinkle-night-200: #cbd2f9;
  --color-twinkle-night-300: #acb4e3;
  --color-twinkle-night-400: #909bd1;
  --color-twinkle-night-500: #7681be;
  --color-twinkle-night-600: #646ea0;
  --color-twinkle-night-700: #505881;
  --color-twinkle-night-800: #394060;
  --color-twinkle-night-900: #272c43;
  --color-twinkle-night-950: #15192b;
}

SCSS

$twinkle-night: #5f699e;
$twinkle-night-rgb: 95, 105, 158;
$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);
}