#1F758D

CSS

:root {
  --celestial: #1f758d;
  --celestial-rgb: 31 117 141;
  --celestial-oklch: oklch(0.524 0.086 221.1);
}

.element {
  color: var(--celestial);
  background-color: hsl(193 64% 34%);
  border-color: oklch(0.524 0.086 221.1);
}

Tailwind CSS v4

@theme {
  --color-celestial: #1f758d;
  --color-celestial-50: #dcfbff;
  --color-celestial-100: #caeffd;
  --color-celestial-200: #adddef;
  --color-celestial-300: #86c2d8;
  --color-celestial-400: #60aac2;
  --color-celestial-500: #3693ae;
  --color-celestial-600: #307c93;
  --color-celestial-700: #266476;
  --color-celestial-800: #194957;
  --color-celestial-900: #10333c;
  --color-celestial-950: #031e26;
}

SCSS

$celestial: #1f758d;
$celestial-rgb: 31, 117, 141;
$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);
}