diff --git a/docs/conf.py b/docs/conf.py
index 5d16b30..ac6fe2f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -94,9 +94,7 @@
     "path_to_docs": "docs",
     "use_repository_button": True,
     "use_issues_button": True,
-    "launch_buttons": {
-        "thebelab": True
-    }
+    "launch_buttons": {"thebelab": True},
 }
 
 # Add any paths that contain custom static files (such as style sheets) here,
diff --git a/setup.py b/setup.py
index 92a06ad..6e2aa31 100644
--- a/setup.py
+++ b/setup.py
@@ -23,13 +23,11 @@
     url="https://github.com/executablebooks/sphinx-thebelab",
     license="MIT License",
     packages=find_packages(),
-    package_data={
-        "sphinx_thebelab": [
-            "_static/thebelab.css",
-            "_static/thebelab.js",
-        ]
-    },
+    package_data={"sphinx_thebelab": ["_static/thebelab.css", "_static/thebelab.js",]},
     classifiers=["License :: OSI Approved :: MIT License"],
     install_requires=["sphinx>=1.8"],
-    extras_require={"sphinx": ["myst-parser[sphinx]"], "testing": ["pytest", "pytest-regressions", "beautifulsoup4"]},
+    extras_require={
+        "sphinx": ["myst-parser[sphinx]", "sphinx-book-theme"],
+        "testing": ["pytest", "pytest-regressions", "beautifulsoup4"],
+    },
 )
diff --git a/sphinx_thebelab/__init__.py b/sphinx_thebelab/__init__.py
index 3009c13..352396f 100644
--- a/sphinx_thebelab/__init__.py
+++ b/sphinx_thebelab/__init__.py
@@ -7,7 +7,7 @@
 
 from pathlib import Path
 
-__version__ = "0.0.6dev0"
+__version__ = "0.0.5dev0"
 
 logger = logging.getLogger(__name__)
 
@@ -22,12 +22,13 @@ def init_thebe_default_config(app, env, docnames):
     defaults = {
         "selector": ".thebe",
         "selector_input": "pre",
-        "selector_output": ".output"
+        "selector_output": ".output",
     }
     for key, val in defaults.items():
         if key not in thebe_config:
             thebe_config[key] = val
 
+
 def init_thebelab_core(app, env):
     config_thebe = app.config["thebe_config"]
     if not config_thebe:
diff --git a/tests/test_build.py b/tests/test_build.py
index 4ddb89e..9ce7568 100644
--- a/tests/test_build.py
+++ b/tests/test_build.py
@@ -54,7 +54,9 @@ def test_sphinx_thebelab(file_regression, sphinx_build):
     file_regression.check(config.prettify(), basename="config_index", extension=".html")
 
     # Testing the configure page which has a custom kernel
-    soup_conf = BeautifulSoup(Path(sphinx_build.path_pg_config).read_text(), "html.parser")
+    soup_conf = BeautifulSoup(
+        Path(sphinx_build.path_pg_config).read_text(), "html.parser"
+    )
     config = soup_conf("script", {"type": "text/x-thebe-config"})
     assert len(config) == 1
     config = config[0]