#12A9C3

CSS

:root {
  --true-sky-blue: #12a9c3;
  --true-sky-blue-rgb: 18 169 195;
  --true-sky-blue-oklch: oklch(0.677 0.117 214.2);
}

.element {
  color: var(--true-sky-blue);
  background-color: hsl(189 83% 42%);
  border-color: oklch(0.677 0.117 214.2);
}

Tailwind CSS v4

@theme {
  --color-true-sky-blue: #12a9c3;
  --color-true-sky-blue-50: #d1feff;
  --color-true-sky-blue-100: #bcf2ff;
  --color-true-sky-blue-200: #9ae1f4;
  --color-true-sky-blue-300: #6bc7de;
  --color-true-sky-blue-400: #32b0c8;
  --color-true-sky-blue-500: #0099b5;
  --color-true-sky-blue-600: #008199;
  --color-true-sky-blue-700: #00677b;
  --color-true-sky-blue-800: #004c5a;
  --color-true-sky-blue-900: #00353f;
  --color-true-sky-blue-950: #002028;
}

SCSS

$true-sky-blue: #12a9c3;
$true-sky-blue-rgb: 18, 169, 195;
$true-sky-blue-light: mix(#fff, $true-sky-blue, 20%);
$true-sky-blue-dark: mix(#000, $true-sky-blue, 20%);

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