#9FD9F4

CSS

:root {
  --over-the-sky: #9fd9f4;
  --over-the-sky-rgb: 159 217 244;
  --over-the-sky-oklch: oklch(0.855 0.07 228.4);
}

.element {
  color: var(--over-the-sky);
  background-color: hsl(199 79% 79%);
  border-color: oklch(0.855 0.07 228.4);
}

Tailwind CSS v4

@theme {
  --color-over-the-sky: #9fd9f4;
  --color-over-the-sky-50: #e2f9ff;
  --color-over-the-sky-100: #d1edfb;
  --color-over-the-sky-200: #b7daed;
  --color-over-the-sky-300: #93bfd5;
  --color-over-the-sky-400: #72a7bf;
  --color-over-the-sky-500: #508fab;
  --color-over-the-sky-600: #457990;
  --color-over-the-sky-700: #376174;
  --color-over-the-sky-800: #264755;
  --color-over-the-sky-900: #19313b;
  --color-over-the-sky-950: #0a1d25;
}

SCSS

$over-the-sky: #9fd9f4;
$over-the-sky-rgb: 159, 217, 244;
$over-the-sky-light: mix(#fff, $over-the-sky, 20%);
$over-the-sky-dark: mix(#000, $over-the-sky, 20%);

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