#A1ABD3

CSS

:root {
  --old-world: #a1abd3;
  --old-world-rgb: 161 171 211;
  --old-world-oklch: oklch(0.747 0.059 273.9);
}

.element {
  color: var(--old-world);
  background-color: hsl(228 36% 73%);
  border-color: oklch(0.747 0.059 273.9);
}

Tailwind CSS v4

@theme {
  --color-old-world: #a1abd3;
  --color-old-world-50: #f0f4ff;
  --color-old-world-100: #e2e7fc;
  --color-old-world-200: #cdd3ee;
  --color-old-world-300: #afb5d6;
  --color-old-world-400: #939cc2;
  --color-old-world-500: #7a84ae;
  --color-old-world-600: #677093;
  --color-old-world-700: #525976;
  --color-old-world-800: #3b4157;
  --color-old-world-900: #282d3d;
  --color-old-world-950: #161a26;
}

SCSS

$old-world: #a1abd3;
$old-world-rgb: 161, 171, 211;
$old-world-light: mix(#fff, $old-world, 20%);
$old-world-dark: mix(#000, $old-world, 20%);

.element {
  color: $old-world;
  box-shadow: 0 0 0 2px rgba($old-world, 0.35);
}