#6B91AF

CSS

:root {
  --heavenly-sky: #6b91af;
  --heavenly-sky-rgb: 107 145 175;
  --heavenly-sky-oklch: oklch(0.64 0.062 242.7);
}

.element {
  color: var(--heavenly-sky);
  background-color: hsl(206 30% 55%);
  border-color: oklch(0.64 0.062 242.7);
}

Tailwind CSS v4

@theme {
  --color-heavenly-sky: #6b91af;
  --color-heavenly-sky-50: #e7f8ff;
  --color-heavenly-sky-100: #d7ebfc;
  --color-heavenly-sky-200: #bfd8ed;
  --color-heavenly-sky-300: #9ebbd5;
  --color-heavenly-sky-400: #7fa3c0;
  --color-heavenly-sky-500: #618bac;
  --color-heavenly-sky-600: #537691;
  --color-heavenly-sky-700: #425e75;
  --color-heavenly-sky-800: #2f4556;
  --color-heavenly-sky-900: #1f303c;
  --color-heavenly-sky-950: #0f1c26;
}

SCSS

$heavenly-sky: #6b91af;
$heavenly-sky-rgb: 107, 145, 175;
$heavenly-sky-light: mix(#fff, $heavenly-sky, 20%);
$heavenly-sky-dark: mix(#000, $heavenly-sky, 20%);

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