Is it best to introduce themes such as dark and light themes in Bootstrap 5 using CSS/SCSS, JavaScript, or a combination of both? Should we create a separate CSS file like dark.css to overwrite classes? Or should we use JavaScript to switch classes like bg-dark, bg-light, etc? I have tried implementing this solution, but I believe there may be a more comprehensive approach that accommodates all requirements. Additionally, if we desire more than just two themes other than dark and white, what would be the best course of action?