On http://ocsigen.org/js_of_ocaml/5.1.0/api/index.html, odoc.css is not found. Yet, it is available in https://github.com/ocsigen/js_of_ocaml/blob/gh-pages/5.1.0/api/_odoc_support/odoc.css.

After searching more, it could be an issue with github pages and directories with leading underscores.

• https://github.blog/2009-12-29-bypassing-jekyll-on-github-pages/
• underscore folder problem with github pages mpetrovich/stylemark#65

Originally posted by @hhugo in #6913 (comment)