#6473A4

CSS

:root {
  --twinkle-night: #6473a4;
  --twinkle-night-rgb: 100 115 164;
  --twinkle-night-oklch: oklch(0.563 0.078 270.7);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(226 26% 52%);
  border-color: oklch(0.563 0.078 270.7);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6473a4;
  --color-twinkle-night-50: #edf4ff;
  --color-twinkle-night-100: #dfe7ff;
  --color-twinkle-night-200: #c9d3f7;
  --color-twinkle-night-300: #aab5e0;
  --color-twinkle-night-400: #8d9cce;
  --color-twinkle-night-500: #7283bb;
  --color-twinkle-night-600: #616f9e;
  --color-twinkle-night-700: #4d597e;
  --color-twinkle-night-800: #37415e;
  --color-twinkle-night-900: #262d42;
  --color-twinkle-night-950: #141a2a;
}

SCSS

$twinkle-night: #6473a4;
$twinkle-night-rgb: 100, 115, 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);
}