#1D4ED8

CSS

:root {
  --flying-fish-blue: #1d4ed8;
  --flying-fish-blue-rgb: 29 78 216;
  --flying-fish-blue-oklch: oklch(0.488 0.217 264.4);
}

.element {
  color: var(--flying-fish-blue);
  background-color: hsl(224 76% 48%);
  border-color: oklch(0.488 0.217 264.4);
}

Tailwind CSS v4

@theme {
  --color-flying-fish-blue: #1d4ed8;
  --color-flying-fish-blue-50: #d8f4ff;
  --color-flying-fish-blue-100: #c6e7ff;
  --color-flying-fish-blue-200: #a9d1ff;
  --color-flying-fish-blue-300: #84b1ff;
  --color-flying-fish-blue-400: #5c95ff;
  --color-flying-fish-blue-500: #3976ff;
  --color-flying-fish-blue-600: #3165e8;
  --color-flying-fish-blue-700: #2751ba;
  --color-flying-fish-blue-800: #143b8c;
  --color-flying-fish-blue-900: #0d2963;
  --color-flying-fish-blue-950: #021644;
}

SCSS

$flying-fish-blue: #1d4ed8;
$flying-fish-blue-rgb: 29, 78, 216;
$flying-fish-blue-light: mix(#fff, $flying-fish-blue, 20%);
$flying-fish-blue-dark: mix(#000, $flying-fish-blue, 20%);

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