#428178

CSS

:root {
  --turquoise-tortoise: #428178;
  --turquoise-tortoise-rgb: 66 129 120;
  --turquoise-tortoise-oklch: oklch(0.559 0.067 183.5);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(171 32% 38%);
  border-color: oklch(0.559 0.067 183.5);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #428178;
  --color-turquoise-tortoise-50: #e1fcf8;
  --color-turquoise-tortoise-100: #d0f0eb;
  --color-turquoise-tortoise-200: #b5ded8;
  --color-turquoise-tortoise-300: #91c3bc;
  --color-turquoise-tortoise-400: #70aca2;
  --color-turquoise-tortoise-500: #4e958b;
  --color-turquoise-tortoise-600: #437e75;
  --color-turquoise-tortoise-700: #35655e;
  --color-turquoise-tortoise-800: #264a44;
  --color-turquoise-tortoise-900: #19332f;
  --color-turquoise-tortoise-950: #091f1b;
}

SCSS

$turquoise-tortoise: #428178;
$turquoise-tortoise-rgb: 66, 129, 120;
$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);
}