#25758F

CSS

:root {
  --celestial: #25758f;
  --celestial-rgb: 37 117 143;
  --celestial-oklch: oklch(0.526 0.085 223.9);
}

.element {
  color: var(--celestial);
  background-color: hsl(195 59% 35%);
  border-color: oklch(0.526 0.085 223.9);
}

Tailwind CSS v4

@theme {
  --color-celestial: #25758f;
  --color-celestial-50: #ddfbff;
  --color-celestial-100: #cbeefe;
  --color-celestial-200: #aeddf0;
  --color-celestial-300: #88c1d9;
  --color-celestial-400: #63aac4;
  --color-celestial-500: #3a92b0;
  --color-celestial-600: #337c94;
  --color-celestial-700: #296377;
  --color-celestial-800: #1b4957;
  --color-celestial-900: #11333d;
  --color-celestial-950: #041e27;
}

SCSS

$celestial: #25758f;
$celestial-rgb: 37, 117, 143;
$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);
}