#407F8E

CSS

:root {
  --mysterious-blue: #407f8e;
  --mysterious-blue-rgb: 64 127 142;
  --mysterious-blue-oklch: oklch(0.561 0.069 215.3);
}

.element {
  color: var(--mysterious-blue);
  background-color: hsl(192 38% 40%);
  border-color: oklch(0.561 0.069 215.3);
}

Tailwind CSS v4

@theme {
  --color-mysterious-blue: #407f8e;
  --color-mysterious-blue-50: #e0fbff;
  --color-mysterious-blue-100: #cfeef7;
  --color-mysterious-blue-200: #b4dce8;
  --color-mysterious-blue-300: #90c1cf;
  --color-mysterious-blue-400: #6ea9b8;
  --color-mysterious-blue-500: #4b92a3;
  --color-mysterious-blue-600: #407b8a;
  --color-mysterious-blue-700: #33636e;
  --color-mysterious-blue-800: #234951;
  --color-mysterious-blue-900: #183238;
  --color-mysterious-blue-950: #081e23;
}

SCSS

$mysterious-blue: #407f8e;
$mysterious-blue-rgb: 64, 127, 142;
$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);
}