#587521

CSS

:root {
  --over-the-hills: #587521;
  --over-the-hills-rgb: 88 117 33;
  --over-the-hills-oklch: oklch(0.522 0.115 126.6);
}

.element {
  color: var(--over-the-hills);
  background-color: hsl(81 56% 29%);
  border-color: oklch(0.522 0.115 126.6);
}

Tailwind CSS v4

@theme {
  --color-over-the-hills: #587521;
  --color-over-the-hills-50: #ebfcd9;
  --color-over-the-hills-100: #dcf0c7;
  --color-over-the-hills-200: #c5deaa;
  --color-over-the-hills-300: #a6c383;
  --color-over-the-hills-400: #8dab5e;
  --color-over-the-hills-500: #729437;
  --color-over-the-hills-600: #617d30;
  --color-over-the-hills-700: #4d6426;
  --color-over-the-hills-800: #3a4918;
  --color-over-the-hills-900: #27330f;
  --color-over-the-hills-950: #161e03;
}

SCSS

$over-the-hills: #587521;
$over-the-hills-rgb: 88, 117, 33;
$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);
}