#457C8A

CSS

:root {
  --mysterious-blue: #457c8a;
  --mysterious-blue-rgb: 69 124 138;
  --mysterious-blue-oklch: oklch(0.554 0.062 216.1);
}

.element {
  color: var(--mysterious-blue);
  background-color: hsl(192 33% 41%);
  border-color: oklch(0.554 0.062 216.1);
}

Tailwind CSS v4

@theme {
  --color-mysterious-blue: #457c8a;
  --color-mysterious-blue-50: #e3faff;
  --color-mysterious-blue-100: #d2edf6;
  --color-mysterious-blue-200: #b8dbe6;
  --color-mysterious-blue-300: #94c0cd;
  --color-mysterious-blue-400: #74a8b6;
  --color-mysterious-blue-500: #5391a1;
  --color-mysterious-blue-600: #477a88;
  --color-mysterious-blue-700: #38626d;
  --color-mysterious-blue-800: #274850;
  --color-mysterious-blue-900: #1a3237;
  --color-mysterious-blue-950: #0b1e22;
}

SCSS

$mysterious-blue: #457c8a;
$mysterious-blue-rgb: 69, 124, 138;
$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);
}