I have been working on Bootstrap 5 theming from two different angles. My first project, bootstrap-dynamic-themes , is a theme creator/editor for Bootstrap 5. The current approach is intentionally conservative: keep the original Bootstrap CSS untouched, then generate additional CSS that overrides Bootstrap variables and component styles where needed. That works, and it has real advantages: It is simple to adopt because projects can keep using standard Bootstrap. It is safer in the sense that Bootstrap itself remains untouched. It is easier to reason about for users who already understand Bootstrap overrides. It can be added or removed without changing the underlying Bootstrap CSS. But it also has a clear downside: as themes become more complete, the generated CSS starts duplicating a lot of Bootstrap behavior. You end up shipping Bootstrap plus a growing override layer. So I started a second project: BootstrapDyn .…