Hugo CSS styles broken on GitHub Pages with a custom domain (baseURL problem?)

[pdurbin]

I followed https://gohugo.io/hosting-and-deployment/hosting-on-github/ and the site looked normal at https://iqss.github.io/hugo.dataverse.org/

Then I added hugo.dataverse.org as a custom domain and the CSS files are trying to come from weird URLs like https://hugo.dataverse.org/hugo.dataverse.org/assets/css/stylesheet.d6fcd20a4fb86efa4dfac8ec95da60244cc8871042183da1ef28e3a762ad79c8.css making the UI unstyled and crazy:

Over at https://discourse.gohugo.io/t/publication-on-github-pages-and-baseurl/43631 there are suggestions like this:

• set baseURL = "/" but all your internal links need to be relative (not the best…)
• add relativeURLs = true but maybe other things will break, you have to check internal links

Here's my current config:

% cat hugo.toml 
baseURL = 'https://hugo.dataverse.org/'
languageCode = 'en-us'
title = 'The Dataverse Project'
theme = 'PaperMod'
[params]
showBreadCrumbs = true

[pdurbin]

In 854a0b4 I changed baseURL to / and it looks normal now. Weird.

I'd like to understand baseURL better.

https://gohugo.io/getting-started/configuration/#baseurl has this to say:

"baseURL
(string) The absolute URL (protocol, host, path, and trailing slash) of your published site (e.g., https://www.example.org/docs/)."

So I feel like I'm doing it wrong. I guess I'll keep this issue open for now.