#637B75

CSS

:root {
  --underwater-world: #637b75;
  --underwater-world-rgb: 99 123 117;
  --underwater-world-oklch: oklch(0.562 0.029 178.3);
}

.element {
  color: var(--underwater-world);
  background-color: hsl(165 11% 44%);
  border-color: oklch(0.562 0.029 178.3);
}

Tailwind CSS v4

@theme {
  --color-underwater-world: #637b75;
  --color-underwater-world-50: #edf8f5;
  --color-underwater-world-100: #deebe8;
  --color-underwater-world-200: #c8d9d5;
  --color-underwater-world-300: #a8bdb8;
  --color-underwater-world-400: #8da49e;
  --color-underwater-world-500: #728d86;
  --color-underwater-world-600: #617772;
  --color-underwater-world-700: #4d5f5b;
  --color-underwater-world-800: #384642;
  --color-underwater-world-900: #26302d;
  --color-underwater-world-950: #151d1a;
}

SCSS

$underwater-world: #637b75;
$underwater-world-rgb: 99, 123, 117;
$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);
}