#597E74

CSS

:root {
  --turquoise-tortoise: #597e74;
  --turquoise-tortoise-rgb: 89 126 116;
  --turquoise-tortoise-oklch: oklch(0.562 0.045 176);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(164 17% 42%);
  border-color: oklch(0.562 0.045 176);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #597e74;
  --color-turquoise-tortoise-50: #e9faf5;
  --color-turquoise-tortoise-100: #d9ede8;
  --color-turquoise-tortoise-200: #c1dbd4;
  --color-turquoise-tortoise-300: #a0bfb7;
  --color-turquoise-tortoise-400: #83a79d;
  --color-turquoise-tortoise-500: #679085;
  --color-turquoise-tortoise-600: #577a71;
  --color-turquoise-tortoise-700: #45625a;
  --color-turquoise-tortoise-800: #324841;
  --color-turquoise-tortoise-900: #22322d;
  --color-turquoise-tortoise-950: #111e1a;
}

SCSS

$turquoise-tortoise: #597e74;
$turquoise-tortoise-rgb: 89, 126, 116;
$turquoise-tortoise-light: mix(#fff, $turquoise-tortoise, 20%);
$turquoise-tortoise-dark: mix(#000, $turquoise-tortoise, 20%);

.element {
  color: $turquoise-tortoise;
  box-shadow: 0 0 0 2px rgba($turquoise-tortoise, 0.35);
}