#406E41

CSS

:root {
  --under-the-radar: #406e41;
  --under-the-radar-rgb: 64 110 65;
  --under-the-radar-oklch: oklch(0.493 0.087 144.6);
}

.element {
  color: var(--under-the-radar);
  background-color: hsl(121 26% 34%);
  border-color: oklch(0.493 0.087 144.6);
}

Tailwind CSS v4

@theme {
  --color-under-the-radar: #406e41;
  --color-under-the-radar-50: #e6fce7;
  --color-under-the-radar-100: #d6f0d7;
  --color-under-the-radar-200: #bddfbf;
  --color-under-the-radar-300: #9bc49e;
  --color-under-the-radar-400: #7eac7e;
  --color-under-the-radar-500: #619561;
  --color-under-the-radar-600: #527e53;
  --color-under-the-radar-700: #426542;
  --color-under-the-radar-800: #304a2e;
  --color-under-the-radar-900: #21331f;
  --color-under-the-radar-950: #101f0f;
}

SCSS

$under-the-radar: #406e41;
$under-the-radar-rgb: 64, 110, 65;
$under-the-radar-light: mix(#fff, $under-the-radar, 20%);
$under-the-radar-dark: mix(#000, $under-the-radar, 20%);

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