#A3A3A3

CSS

:root {
  --shadow-of-the-colossus: #a3a3a3;
  --shadow-of-the-colossus-rgb: 163 163 163;
  --shadow-of-the-colossus-oklch: oklch(0.715 0 0);
}

.element {
  color: var(--shadow-of-the-colossus);
  background-color: hsl(0 0% 64%);
  border-color: oklch(0.715 0 0);
}

Tailwind CSS v4

@theme {
  --color-shadow-of-the-colossus: #a3a3a3;
  --color-shadow-of-the-colossus-50: #f5f5f5;
  --color-shadow-of-the-colossus-100: #e8e8e8;
  --color-shadow-of-the-colossus-200: #d4d4d4;
  --color-shadow-of-the-colossus-300: #b7b7b7;
  --color-shadow-of-the-colossus-400: #9e9e9e;
  --color-shadow-of-the-colossus-500: #868686;
  --color-shadow-of-the-colossus-600: #717171;
  --color-shadow-of-the-colossus-700: #5b5b5b;
  --color-shadow-of-the-colossus-800: #424242;
  --color-shadow-of-the-colossus-900: #2e2e2e;
  --color-shadow-of-the-colossus-950: #1b1b1b;
}

SCSS

$shadow-of-the-colossus: #a3a3a3;
$shadow-of-the-colossus-rgb: 163, 163, 163;
$shadow-of-the-colossus-light: mix(#fff, $shadow-of-the-colossus, 20%);
$shadow-of-the-colossus-dark: mix(#000, $shadow-of-the-colossus, 20%);

.element {
  color: $shadow-of-the-colossus;
  box-shadow: 0 0 0 2px rgba($shadow-of-the-colossus, 0.35);
}