diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 37abed8..fdf7d2b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -57,7 +57,7 @@ jobs:
         uses: nwtgck/actions-netlify@v1.1
         with:
           publish-dir: 'lecture-python-programming.myst/_build/html/'
-          production-branch: master
+          production-branch: main
           github-token: ${{ secrets.GITHUB_TOKEN }}
           deploy-message: "Preview Deploy from GitHub Actions"
         env:
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 5960efa..1e6d1b6 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -2,7 +2,7 @@ name: continuous-integration
 
 on:
   push:
-    branches: [master]
+    branches: [main]
     tags:
       - 'v*'
   pull_request:
diff --git a/src/quantecon_book_theme/__init__.py b/src/quantecon_book_theme/__init__.py
index 0ed1e5c..9a5eafd 100644
--- a/src/quantecon_book_theme/__init__.py
+++ b/src/quantecon_book_theme/__init__.py
@@ -230,8 +230,8 @@ def get_github_src_folder(app):
         if repo_url:
             branch = config_theme.get("repository_branch")
             if not branch:
-                # Explicitly check in cae branch is ""
-                branch = "master"
+                # Explicitly check in case branch is ""
+                branch = "main"
             relpath = config_theme.get("path_to_docs", "")
             org, repo = repo_url.strip("/").split("/")[-2:]
             context.update(
diff --git a/src/quantecon_book_theme/assets/styles/index.scss b/src/quantecon_book_theme/assets/styles/index.scss
index e0bc5dc..1ff36a4 100644
--- a/src/quantecon_book_theme/assets/styles/index.scss
+++ b/src/quantecon_book_theme/assets/styles/index.scss
@@ -1193,13 +1193,13 @@ tt {
   }
 }
 
-div.admonition, .admonition {
+div.admonition,
+.admonition {
   font-size: 0.9rem;
   margin: 1.5rem auto;
   padding: 0 1rem 0.5rem 1rem;
   page-break-inside: avoid;
-  box-shadow: 0 0.2rem 0.5rem rgba(0, 0, 0, 0.1),
-  0 0 0.05rem rgba(0, 0, 0, 0.1);
+  box-shadow: 0 0.2rem 0.5rem rgba(0, 0, 0, 0.1), 0 0 0.05rem rgba(0, 0, 0, 0.1);
   > .admonition-title {
     position: relative;
     margin: 0 -1rem;
diff --git a/src/quantecon_book_theme/launch.py b/src/quantecon_book_theme/launch.py
index 63490b6..7047bb3 100644
--- a/src/quantecon_book_theme/launch.py
+++ b/src/quantecon_book_theme/launch.py
@@ -182,5 +182,5 @@ def _is_notebook(app, pagename):
 def _get_branch(config_theme):
     branch = config_theme.get("nb_branch")
     if not branch:
-        branch = "master"
+        branch = "main"
     return branch
diff --git a/tests/sites/base/conf.py b/tests/sites/base/conf.py
index 3f2a46a..1a382f1 100644
--- a/tests/sites/base/conf.py
+++ b/tests/sites/base/conf.py
@@ -24,7 +24,7 @@
     "repository_url": "https://github.com/executablebooks/sphinx-book-theme",
     "nb_repository_url": "https://github.com/executablebooks/sphinx-book-theme",
     "navigation_with_keys": True,
-    # "repository_branch": "master",  # Not using this, should default to master
+    # "repository_branch": "main",  # Not using this, should default to main
     "launch_buttons": {
         "binderhub_url": "https://mybinder.org",
         "jupyterhub_url": "https://datahub.berkeley.edu",