#557600

CSS

:root {
  --over-the-hills: #557600;
  --over-the-hills-rgb: 85 118 0;
  --over-the-hills-oklch: oklch(0.521 0.134 126.5);
}

.element {
  color: var(--over-the-hills);
  background-color: hsl(77 100% 23%);
  border-color: oklch(0.521 0.134 126.5);
}

Tailwind CSS v4

@theme {
  --color-over-the-hills: #557600;
  --color-over-the-hills-50: #eafdd5;
  --color-over-the-hills-100: #dbf1c2;
  --color-over-the-hills-200: #c3e0a3;
  --color-over-the-hills-300: #a3c57a;
  --color-over-the-hills-400: #8aad50;
  --color-over-the-hills-500: #6f951f;
  --color-over-the-hills-600: #5e7e1d;
  --color-over-the-hills-700: #4b6518;
  --color-over-the-hills-800: #384a0c;
  --color-over-the-hills-900: #263307;
  --color-over-the-hills-950: #151f00;
}

SCSS

$over-the-hills: #557600;
$over-the-hills-rgb: 85, 118, 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);
}