#686FB2

CSS

:root {
  --twinkle-night: #686fb2;
  --twinkle-night-rgb: 104 111 178;
  --twinkle-night-oklch: oklch(0.565 0.104 278);
}

.element {
  color: var(--twinkle-night);
  background-color: hsl(234 32% 55%);
  border-color: oklch(0.565 0.104 278);
}

Tailwind CSS v4

@theme {
  --color-twinkle-night: #686fb2;
  --color-twinkle-night-50: #eff3ff;
  --color-twinkle-night-100: #e0e5ff;
  --color-twinkle-night-200: #cbd0ff;
  --color-twinkle-night-300: #acb2ec;
  --color-twinkle-night-400: #9098db;
  --color-twinkle-night-500: #767eca;
  --color-twinkle-night-600: #646baa;
  --color-twinkle-night-700: #505689;
  --color-twinkle-night-800: #393f66;
  --color-twinkle-night-900: #272b48;
  --color-twinkle-night-950: #15182f;
}

SCSS

$twinkle-night: #686fb2;
$twinkle-night-rgb: 104, 111, 178;
$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);
}