#1B758E

CSS

:root {
  --celestial: #1b758e;
  --celestial-rgb: 27 117 142;
  --celestial-oklch: oklch(0.524 0.088 221.5);
}

.element {
  color: var(--celestial);
  background-color: hsl(193 68% 33%);
  border-color: oklch(0.524 0.088 221.5);
}

Tailwind CSS v4

@theme {
  --color-celestial: #1b758e;
  --color-celestial-50: #dbfbff;
  --color-celestial-100: #c9effe;
  --color-celestial-200: #acddf0;
  --color-celestial-300: #85c2d9;
  --color-celestial-400: #5eaac4;
  --color-celestial-500: #3393b0;
  --color-celestial-600: #2d7c94;
  --color-celestial-700: #246477;
  --color-celestial-800: #174957;
  --color-celestial-900: #0f333d;
  --color-celestial-950: #021e26;
}

SCSS

$celestial: #1b758e;
$celestial-rgb: 27, 117, 142;
$celestial-light: mix(#fff, $celestial, 20%);
$celestial-dark: mix(#000, $celestial, 20%);

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