#3B757B

CSS

:root {
  --ocean-slumber: #3b757b;
  --ocean-slumber-rgb: 59 117 123;
  --ocean-slumber-oklch: oklch(0.526 0.061 204.3);
}

.element {
  color: var(--ocean-slumber);
  background-color: hsl(186 35% 36%);
  border-color: oklch(0.526 0.061 204.3);
}

Tailwind CSS v4

@theme {
  --color-ocean-slumber: #3b757b;
  --color-ocean-slumber-50: #e2fbfe;
  --color-ocean-slumber-100: #d1eef2;
  --color-ocean-slumber-200: #b7dce1;
  --color-ocean-slumber-300: #93c1c7;
  --color-ocean-slumber-400: #72a9af;
  --color-ocean-slumber-500: #519299;
  --color-ocean-slumber-600: #457c81;
  --color-ocean-slumber-700: #376368;
  --color-ocean-slumber-800: #27494c;
  --color-ocean-slumber-900: #1a3234;
  --color-ocean-slumber-950: #0a1e20;
}

SCSS

$ocean-slumber: #3b757b;
$ocean-slumber-rgb: 59, 117, 123;
$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);
}