#3F747C

CSS

:root {
  --ocean-slumber: #3f747c;
  --ocean-slumber-rgb: 63 116 124;
  --ocean-slumber-oklch: oklch(0.525 0.058 208.1);
}

.element {
  color: var(--ocean-slumber);
  background-color: hsl(188 33% 37%);
  border-color: oklch(0.525 0.058 208.1);
}

Tailwind CSS v4

@theme {
  --color-ocean-slumber: #3f747c;
  --color-ocean-slumber-50: #e3fafe;
  --color-ocean-slumber-100: #d3eef3;
  --color-ocean-slumber-200: #b9dce2;
  --color-ocean-slumber-300: #96c0c8;
  --color-ocean-slumber-400: #76a8b0;
  --color-ocean-slumber-500: #55919a;
  --color-ocean-slumber-600: #497b82;
  --color-ocean-slumber-700: #3a6268;
  --color-ocean-slumber-800: #29484c;
  --color-ocean-slumber-900: #1c3235;
  --color-ocean-slumber-950: #0c1e20;
}

SCSS

$ocean-slumber: #3f747c;
$ocean-slumber-rgb: 63, 116, 124;
$ocean-slumber-light: mix(#fff, $ocean-slumber, 20%);
$ocean-slumber-dark: mix(#000, $ocean-slumber, 20%);

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