Restore the mobile sidebar toggles in the docs

docs/source/conf.py

@@ -486,6 +486,14 @@ def gen_csv_suews(path_csv):
     extra_footer=f"""<p>Version: {git_version_string} |
     Commit: <a href="https://github.com/UMEP-dev/SUEWS/commit/{git_commit_full}">{git_commit_short}</a> |
     <a href="https://umep-dev.github.io/SUEWS/brand/showcase.html">Brand</a></p>""",
+    # Keep the PyData top navbar empty, as sphinx_book_theme intends. When this
+    # key is absent, pydata-sphinx-theme 0.20 adds a search field to it, which
+    # renders a hidden navbar carrying its own sidebar toggles; the theme JS
+    # then binds to those hidden buttons and the visible toggles stop opening
+    # the sidebars on mobile. Fixed upstream in
+    # executablebooks/sphinx-book-theme#987 (unreleased as of 1.4.0); drop this
+    # once a release carrying that fix is pinned.
+    navbar_persistent=[],
     # twitter_url="https://twitter.com/xarray_devs",
 )
 

pyproject.toml

@@ -134,7 +134,11 @@ docs = [
     # Documentation - Essential only (based on conf.py usage)
     "sphinx>=7,<9",
     "sphinx-autobuild",
-    "sphinx-book-theme",        # Active theme in conf.py
+    # Active theme in conf.py. Pinned exactly: it pins pydata-sphinx-theme
+    # (==0.20.0 for 1.4.0), and a theme bump can change the header and sidebar
+    # markup the mobile toggles rely on, so upgrade deliberately and recheck
+    # the sidebars at phone width (see navbar_persistent in conf.py).
+    "sphinx-book-theme==1.4.0",
     "pybtex",                   # Bibliography processing
     "sphinxcontrib-bibtex>=2.6,<3", # Bibliography support (heavily customised)
     # Collapsible sections for YAML config docs (>=0.7 supports Sphinx 8)