@function --light-dark(--light, --dark) {
  result: var(--light);
	
  @media (prefers-color-scheme: dark) {
    result: var(--dark);
  }
}

#ghost {
  color: --light-dark(#ffffff, #e4e4e4);

  background-color: --light-dark(#e4e4e4, #333);

  font-size: --light-dark(16px, 1.75rem);

  font-weight: --light-dark(bold, normal);

  background-image: --light-dark(
    url("/assets/img/ghost.svg"),
    url("/assets/img/blinky.svg")
  );
}

This text is based on the system theme.