#537D72

CSS

:root {
  --turquoise-tortoise: #537d72;
  --turquoise-tortoise-rgb: 83 125 114;
  --turquoise-tortoise-oklch: oklch(0.555 0.05 176.2);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(164 20% 41%);
  border-color: oklch(0.555 0.05 176.2);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #537d72;
  --color-turquoise-tortoise-50: #e7faf5;
  --color-turquoise-tortoise-100: #d7eee8;
  --color-turquoise-tortoise-200: #bfdcd4;
  --color-turquoise-tortoise-300: #9dc0b7;
  --color-turquoise-tortoise-400: #80a99d;
  --color-turquoise-tortoise-500: #629185;
  --color-turquoise-tortoise-600: #537b70;
  --color-turquoise-tortoise-700: #42625a;
  --color-turquoise-tortoise-800: #304841;
  --color-turquoise-tortoise-900: #20322d;
  --color-turquoise-tortoise-950: #101e1a;
}

SCSS

$turquoise-tortoise: #537d72;
$turquoise-tortoise-rgb: 83, 125, 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);
}