#447C8B

CSS

:root {
  --mysterious-blue: #447c8b;
  --mysterious-blue-rgb: 68 124 139;
  --mysterious-blue-oklch: oklch(0.554 0.063 217.1);
}

.element {
  color: var(--mysterious-blue);
  background-color: hsl(193 34% 41%);
  border-color: oklch(0.554 0.063 217.1);
}

Tailwind CSS v4

@theme {
  --color-mysterious-blue: #447c8b;
  --color-mysterious-blue-50: #e2faff;
  --color-mysterious-blue-100: #d2edf6;
  --color-mysterious-blue-200: #b7dbe7;
  --color-mysterious-blue-300: #94c0ce;
  --color-mysterious-blue-400: #73a8b7;
  --color-mysterious-blue-500: #5291a2;
  --color-mysterious-blue-600: #467a89;
  --color-mysterious-blue-700: #38626d;
  --color-mysterious-blue-800: #274850;
  --color-mysterious-blue-900: #1a3238;
  --color-mysterious-blue-950: #0a1e22;
}

SCSS

$mysterious-blue: #447c8b;
$mysterious-blue-rgb: 68, 124, 139;
$mysterious-blue-light: mix(#fff, $mysterious-blue, 20%);
$mysterious-blue-dark: mix(#000, $mysterious-blue, 20%);

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