I was waiting to share this until the design stabilized:
Project: GitHub - willfaught/paige: Powerful, pliable pixel perfection. An advanced Hugo theme.
Feedback is very welcome!
Aside from the design, I think it has some really useful shortcodes for figures, images, galleries, and videos. The image processing features were the most complicated code. The features are documented in the readme.
I may make a separate post recounting the things learned, the decisions made, and tips.
Special thanks to @jmooring, @bep, and @razon for their help!