#6368A0

CSS

:root {
  --twinkle-night: #6368a0;
  --twinkle-night-rgb: 99 104 160;
  --twinkle-night-oklch: oklch(0.537 0.088 279.1);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(235 24% 51%);
  border-color: oklch(0.537 0.088 279.1);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #6368a0;
  --color-twinkle-night-50: #f0f3ff;
  --color-twinkle-night-100: #e2e5ff;
  --color-twinkle-night-200: #cdd1fa;
  --color-twinkle-night-300: #afb3e4;
  --color-twinkle-night-400: #9399d2;
  --color-twinkle-night-500: #7a80bf;
  --color-twinkle-night-600: #676ca2;
  --color-twinkle-night-700: #525682;
  --color-twinkle-night-800: #3b3f61;
  --color-twinkle-night-900: #282c44;
  --color-twinkle-night-950: #16192c;
}

SCSS

$twinkle-night: #6368a0;
$twinkle-night-rgb: 99, 104, 160;
$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);
}