How can I get a locally-produced _build/html copy of my book to deploy within GitHub pages?

[kburchfiel]

I would like to deploy a locally-produced HTML copy of a book that I created with Jupyter Book (v1) to GitHub. Here's what my _build/html folder looks like on my desktop:

When I open up the index.html folder from this project on my local computer, I get the output that I would expect:

I then copied all contents of that folder into my GitHub project's docs folder; you can view that folder here. I also configured my GitHub Pages settings to deploy from the /docs branch of my project:

However, when I actually try accessing the site, it's clear that something isn't working. HTML-based text appears to be coming through, but there doesn't seem to be any CSS active, and images aren't appearing either.

I understand that I'm taking a more manual approach than the GitHub Actions-based one that Jupyter Book recommends, but I'd love to get my current approach to work if possible. If I'm missing a simple step or two that would allow me to successfully deploy this site on GitHub Pages by (1) building the HTML site locally, (2) copying it into my repository's docs/ folder, and (3) then committing a new copy of the project to GitHub, please let me know!