#D6EBEE

CSS

:root {
  --castle-in-the-sky: #d6ebee;
  --castle-in-the-sky-rgb: 214 235 238;
  --castle-in-the-sky-oklch: oklch(0.925 0.023 207.1);
}

.element {
  color: var(--castle-in-the-sky);
  background-color: hsl(188 41% 89%);
  border-color: oklch(0.925 0.023 207.1);
}

Tailwind CSS v4

@theme {
  --color-castle-in-the-sky: #d6ebee;
  --color-castle-in-the-sky-50: #eef7f9;
  --color-castle-in-the-sky-100: #e0eaec;
  --color-castle-in-the-sky-200: #cad7d9;
  --color-castle-in-the-sky-300: #abbbbe;
  --color-castle-in-the-sky-400: #90a2a5;
  --color-castle-in-the-sky-500: #758b8e;
  --color-castle-in-the-sky-600: #647578;
  --color-castle-in-the-sky-700: #4f5e60;
  --color-castle-in-the-sky-800: #3a4546;
  --color-castle-in-the-sky-900: #273030;
  --color-castle-in-the-sky-950: #161c1d;
}

SCSS

$castle-in-the-sky: #d6ebee;
$castle-in-the-sky-rgb: 214, 235, 238;
$castle-in-the-sky-light: mix(#fff, $castle-in-the-sky, 20%);
$castle-in-the-sky-dark: mix(#000, $castle-in-the-sky, 20%);

.element {
  color: $castle-in-the-sky;
  box-shadow: 0 0 0 2px rgba($castle-in-the-sky, 0.35);
}