#647974

CSS

:root {
  --underwater-world: #647974;
  --underwater-world-rgb: 100 121 116;
  --underwater-world-oklch: oklch(0.558 0.026 179.3);
}

.element {
  color: var(--underwater-world);
  background-color: hsl(166 10% 43%);
  border-color: oklch(0.558 0.026 179.3);
}

Tailwind CSS v4

@theme {
  --color-underwater-world: #647974;
  --color-underwater-world-50: #eef8f5;
  --color-underwater-world-100: #dfebe8;
  --color-underwater-world-200: #c9d8d5;
  --color-underwater-world-300: #aabcb8;
  --color-underwater-world-400: #8fa49f;
  --color-underwater-world-500: #748c86;
  --color-underwater-world-600: #637772;
  --color-underwater-world-700: #4f5f5b;
  --color-underwater-world-800: #394542;
  --color-underwater-world-900: #27302e;
  --color-underwater-world-950: #151c1a;
}

SCSS

$underwater-world: #647974;
$underwater-world-rgb: 100, 121, 116;
$underwater-world-light: mix(#fff, $underwater-world, 20%);
$underwater-world-dark: mix(#000, $underwater-world, 20%);

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