#1FA9BF

CSS

:root {
  --true-sky-blue: #1fa9bf;
  --true-sky-blue-rgb: 31 169 191;
  --true-sky-blue-oklch: oklch(0.676 0.112 211.8);
}

.element {
  color: var(--true-sky-blue);
  background-color: hsl(188 72% 44%);
  border-color: oklch(0.676 0.112 211.8);
}

Tailwind CSS v4

@theme {
  --color-true-sky-blue: #1fa9bf;
  --color-true-sky-blue-50: #d2feff;
  --color-true-sky-blue-100: #bef2ff;
  --color-true-sky-blue-200: #9ce1f1;
  --color-true-sky-blue-300: #6ec7da;
  --color-true-sky-blue-400: #38b0c5;
  --color-true-sky-blue-500: #0099b1;
  --color-true-sky-blue-600: #008195;
  --color-true-sky-blue-700: #006778;
  --color-true-sky-blue-800: #004c58;
  --color-true-sky-blue-900: #00353d;
  --color-true-sky-blue-950: #002027;
}

SCSS

$true-sky-blue: #1fa9bf;
$true-sky-blue-rgb: 31, 169, 191;
$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);
}