#557F72

CSS

:root {
  --turquoise-tortoise: #557f72;
  --turquoise-tortoise-rgb: 85 127 114;
  --turquoise-tortoise-oklch: oklch(0.562 0.051 173);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(161 20% 42%);
  border-color: oklch(0.562 0.051 173);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #557f72;
  --color-turquoise-tortoise-50: #e7faf4;
  --color-turquoise-tortoise-100: #d7eee7;
  --color-turquoise-tortoise-200: #bfdcd3;
  --color-turquoise-tortoise-300: #9dc0b6;
  --color-turquoise-tortoise-400: #80a99b;
  --color-turquoise-tortoise-500: #629283;
  --color-turquoise-tortoise-600: #547b6f;
  --color-turquoise-tortoise-700: #436359;
  --color-turquoise-tortoise-800: #304840;
  --color-turquoise-tortoise-900: #21322c;
  --color-turquoise-tortoise-950: #101e19;
}

SCSS

$turquoise-tortoise: #557f72;
$turquoise-tortoise-rgb: 85, 127, 114;
$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);
}