#647B7A

CSS

:root {
  --underwater-world: #647b7a;
  --underwater-world-rgb: 100 123 122;
  --underwater-world-oklch: oklch(0.564 0.027 193.2);
}

.element {
  color: var(--underwater-world);
  background-color: hsl(177 10% 44%);
  border-color: oklch(0.564 0.027 193.2);
}

Tailwind CSS v4

@theme {
  --color-underwater-world: #647b7a;
  --color-underwater-world-50: #edf8f7;
  --color-underwater-world-100: #deebeb;
  --color-underwater-world-200: #c8d8d8;
  --color-underwater-world-300: #a8bcbc;
  --color-underwater-world-400: #8da4a3;
  --color-underwater-world-500: #728c8b;
  --color-underwater-world-600: #617776;
  --color-underwater-world-700: #4d5f5e;
  --color-underwater-world-800: #384545;
  --color-underwater-world-900: #26302f;
  --color-underwater-world-950: #151c1c;
}

SCSS

$underwater-world: #647b7a;
$underwater-world-rgb: 100, 123, 122;
$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);
}