#3FA7C3

CSS

:root {
  --true-sky-blue: #3fa7c3;
  --true-sky-blue-rgb: 63 167 195;
  --true-sky-blue-oklch: oklch(0.68 0.102 219.1);
}

.element {
  color: var(--true-sky-blue);
  background-color: hsl(193 52% 51%);
  border-color: oklch(0.68 0.102 219.1);
}

Tailwind CSS v4

@theme {
  --color-true-sky-blue: #3fa7c3;
  --color-true-sky-blue-50: #d6fdff;
  --color-true-sky-blue-100: #c3f0ff;
  --color-true-sky-blue-200: #a4dff3;
  --color-true-sky-blue-300: #7ac4dc;
  --color-true-sky-blue-400: #4dadc7;
  --color-true-sky-blue-500: #0095b4;
  --color-true-sky-blue-600: #0d7e98;
  --color-true-sky-blue-700: #0c657a;
  --color-true-sky-blue-800: #044b59;
  --color-true-sky-blue-900: #04343e;
  --color-true-sky-blue-950: #001f28;
}

SCSS

$true-sky-blue: #3fa7c3;
$true-sky-blue-rgb: 63, 167, 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);
}