#004250

CSS

:root {
  --cold-and-dark: #004250;
  --cold-and-dark-rgb: 0 66 80;
  --cold-and-dark-oklch: oklch(0.35 0.063 217.7);
}

.element {
  color: var(--cold-and-dark);
  background-color: hsl(191 100% 16%);
  border-color: oklch(0.35 0.063 217.7);
}

Tailwind CSS v4

@theme {
  --color-cold-and-dark: #004250;
  --color-cold-and-dark-50: #e2faff;
  --color-cold-and-dark-100: #d2edf6;
  --color-cold-and-dark-200: #b8dbe7;
  --color-cold-and-dark-300: #94c0ce;
  --color-cold-and-dark-400: #73a8b7;
  --color-cold-and-dark-500: #5391a2;
  --color-cold-and-dark-600: #477a89;
  --color-cold-and-dark-700: #38626e;
  --color-cold-and-dark-800: #274850;
  --color-cold-and-dark-900: #1a3238;
  --color-cold-and-dark-950: #0a1e22;
}

SCSS

$cold-and-dark: #004250;
$cold-and-dark-rgb: 0, 66, 80;
$cold-and-dark-light: mix(#fff, $cold-and-dark, 20%);
$cold-and-dark-dark: mix(#000, $cold-and-dark, 20%);

.element {
  color: $cold-and-dark;
  box-shadow: 0 0 0 2px rgba($cold-and-dark, 0.35);
}