Unexpected font/styling in newly rendered documentation after updating sphinx-book-theme and pydata-sphinx-theme

Describe the bug

context

Hello!

I've been using the Sphinx book theme for my personal project's documentation because I like the simplistic styling. However, the HTML version that I rendered today using sphinx-build ... looks completely different from my previous version that I committed to GitHub a while ago (see image below for comparison).

Notably,

fonts and styling are completely different,
the "Theme by the Executable Book Project" in the sidebar disappeared, but
there is now a toggle for light/dark mode, which is pretty neat.

I suspect this has to do with my updating of sphinx-book-theme today since I also upgraded a bunch of other libraries, but is there a way to revert to the old styling without downgrading? I did not make any changes to conf.py or index.rst (or anything else related to Sphinx); I simply ran sphinx-build ... as I would normally.

Edit: I can confirm that downgrading from sphinx-book-theme=1.0.1 and pydata-sphinx-theme=0.13.3 to sphinx-book-theme=0.3.3 and pydata-sphinx-theme=0.8.1 gives me back the old font/styling.

expectation

I expected the old and new versions of my documentation to have the same font/styling.

bug

But instead, the new HTML render of my documentation looks completely different.

Reproduce the bug

Run sphinx-build -b html . .. in the <project>/docs/source directory.

The relevant configuration options in my conf.py file are below:

# -- General configuration ---------------------------------------------------

extensions = [
    "numpydoc",
    "sphinx.ext.autodoc",
    "sphinx.ext.autosummary",
    "sphinx.ext.doctest",
    "sphinx.ext.duration",
    "sphinx.ext.intersphinx",
    "sphinx.ext.napoleon",
    "sphinx.ext.viewcode"
]

autosummary_generate = True
exclude_patterns = []
intersphinx_mapping = {
    "numpy": ("https://numpy.org/doc/stable/", None),
    "python": ("https://docs.python.org/3/", None)
}
numpydoc_show_class_members = False
templates_path = ["_templates"]

# -- Options for HTML output -------------------------------------------------

html_show_sourcelink = False
html_static_path = ["_static"]
html_theme = "sphinx_book_theme"
html_theme_options = {
    "home_page_in_toc": True,
    "path_to_docs": "docs/",
    "repository_url": "https://github.com/bbye98/minim",
    "use_edit_page_button": True,
    "use_issues_button": True,
    "use_repository_button": True
}

List your environment

❯ conda list -f pydata-sphinx-theme
# packages in environment at /home/bye/miniconda3:
#
# Name                    Version                   Build  Channel
pydata-sphinx-theme       0.13.3             pyhd8ed1ab_0    conda-forge

❯ conda list -f sphinx-book-theme
# packages in environment at /home/bye/miniconda3:
#
# Name                    Version                   Build  Channel
sphinx-book-theme         1.0.1              pyhd8ed1ab_0    conda-forge

❯ python
Python 3.9.16 | packaged by conda-forge | (main, Feb  1 2023, 21:39:03)
[GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()

❯ uname -a
Linux DESKTOP-****** 5.15.90.1-microsoft-standard-WSL2 #1 SMP Fri Jan 27 02:56:13 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

executablebooks / sphinx-book-theme