Tailwind out of the box is a simple, canned design system. The Tailwind authors have already decided your color palette, spacings, animations, etc. This is perfectly fine for prototypes or anything that isn't that important. But if you want to have more ownership over the design system, it's better to use Tailwind's config and set it up as it makes sense for your site. Colors are the most obvious candidates, with Tailwind you can setup your own colors and from there do `bg-active` or whatever else makes sense for your site. You can define whatever is important for your site, and fall back to the inbuilt system for the things that aren't.