Nebula

Nebula is a WordPress theme framework that focuses on enhancing development. The core features of Nebula make it a powerful tool for designing, developing, and analyzing WordPress websites consistently, yet its deliberately uncomplicated code syntax also serves as a learning resource for programmers themselves. Maintained by chrisblakley on GitHub, where it has earned 144 stars from the community.

It's actively developed around wordpress, theme, child-theme, and is a solid reference for anyone building with these tools.