#3F817D

CSS

:root {
  --turquoise-tortoise: #3f817d;
  --turquoise-tortoise-rgb: 63 129 125;
  --turquoise-tortoise-oklch: oklch(0.559 0.068 190.2);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(176 34% 38%);
  border-color: oklch(0.559 0.068 190.2);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #3f817d;
  --color-turquoise-tortoise-50: #e0fcfa;
  --color-turquoise-tortoise-100: #cff0ee;
  --color-turquoise-tortoise-200: #b4dedc;
  --color-turquoise-tortoise-300: #8fc3c0;
  --color-turquoise-tortoise-400: #6eaca7;
  --color-turquoise-tortoise-500: #4a9590;
  --color-turquoise-tortoise-600: #407e7a;
  --color-turquoise-tortoise-700: #336562;
  --color-turquoise-tortoise-800: #244a47;
  --color-turquoise-tortoise-900: #183331;
  --color-turquoise-tortoise-950: #081f1d;
}

SCSS

$turquoise-tortoise: #3f817d;
$turquoise-tortoise-rgb: 63, 129, 125;
$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);
}