#9FD9F1

CSS

:root {
  --over-the-sky: #9fd9f1;
  --over-the-sky-rgb: 159 217 241;
  --over-the-sky-oklch: oklch(0.854 0.068 225.5);
}

.element {
  color: var(--over-the-sky);
  background-color: hsl(198 75% 78%);
  border-color: oklch(0.854 0.068 225.5);
}

Tailwind CSS v4

@theme {
  --color-over-the-sky: #9fd9f1;
  --color-over-the-sky-50: #e2faff;
  --color-over-the-sky-100: #d1edfa;
  --color-over-the-sky-200: #b7dbeb;
  --color-over-the-sky-300: #93bfd3;
  --color-over-the-sky-400: #72a7bd;
  --color-over-the-sky-500: #5190a8;
  --color-over-the-sky-600: #457a8e;
  --color-over-the-sky-700: #376172;
  --color-over-the-sky-800: #264854;
  --color-over-the-sky-900: #19323a;
  --color-over-the-sky-950: #0a1e24;
}

SCSS

$over-the-sky: #9fd9f1;
$over-the-sky-rgb: 159, 217, 241;
$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);
}