#99CDC8

CSS

:root {
  --pastel-turquoise: #99cdc8;
  --pastel-turquoise-rgb: 153 205 200;
  --pastel-turquoise-oklch: oklch(0.811 0.054 188.8);
}

.element {
  color: var(--pastel-turquoise);
  background-color: hsl(174 34% 70%);
  border-color: oklch(0.811 0.054 188.8);
}

Tailwind CSS v4

@theme {
  --color-pastel-turquoise: #99cdc8;
  --color-pastel-turquoise-50: #e4faf9;
  --color-pastel-turquoise-100: #d4eeec;
  --color-pastel-turquoise-200: #bbdcda;
  --color-pastel-turquoise-300: #98c1be;
  --color-pastel-turquoise-400: #79a9a5;
  --color-pastel-turquoise-500: #5a928d;
  --color-pastel-turquoise-600: #4d7c77;
  --color-pastel-turquoise-700: #3d6360;
  --color-pastel-turquoise-800: #2c4945;
  --color-pastel-turquoise-900: #1d3230;
  --color-pastel-turquoise-950: #0d1e1c;
}

SCSS

$pastel-turquoise: #99cdc8;
$pastel-turquoise-rgb: 153, 205, 200;
$pastel-turquoise-light: mix(#fff, $pastel-turquoise, 20%);
$pastel-turquoise-dark: mix(#000, $pastel-turquoise, 20%);

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