#3F6B00

CSS

:root {
  --over-the-hills: #3f6b00;
  --over-the-hills-rgb: 63 107 0;
  --over-the-hills-oklch: oklch(0.477 0.132 132);
}

.element {
  color: var(--over-the-hills);
  background-color: hsl(85 100% 21%);
  border-color: oklch(0.477 0.132 132);
}

Tailwind CSS v4

@theme {
  --color-over-the-hills: #3f6b00;
  --color-over-the-hills-50: #e6fed8;
  --color-over-the-hills-100: #d6f2c6;
  --color-over-the-hills-200: #bde1a8;
  --color-over-the-hills-300: #9bc780;
  --color-over-the-hills-400: #81af59;
  --color-over-the-hills-500: #64972f;
  --color-over-the-hills-600: #55802a;
  --color-over-the-hills-700: #446721;
  --color-over-the-hills-800: #334b13;
  --color-over-the-hills-900: #23340c;
  --color-over-the-hills-950: #121f01;
}

SCSS

$over-the-hills: #3f6b00;
$over-the-hills-rgb: 63, 107, 0;
$over-the-hills-light: mix(#fff, $over-the-hills, 20%);
$over-the-hills-dark: mix(#000, $over-the-hills, 20%);

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