diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 0e2c1c8..a50e1f2 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -10,29 +10,33 @@ on:
 
 jobs:
   test:
-    runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        ruby-version: [2.7]
-
-    steps:
-    - uses: actions/checkout@v2
-    - name: Set up Ruby
-      uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: ${{ matrix.ruby-version }}
-
-    - uses: actions/cache@v1
-      with:
-        path: vendor/bundle
-        key: gems-${{ runner.os }}-${{ matrix.ruby-version }}-${{ hashFiles('**/Gemfile.lock') }}
-
-    # necessary to get ruby 2.3 to work nicely with bundler vendor/bundle cache
-    # can remove once ruby 2.3 is no longer supported
-    - run: gem update --system 3.4.22
-
-    - run: bundle config set deployment 'true'
-    - run: bundle install
-
-    - run: bundle exec middleman build
+    -runs:
+      using: 'docker'
+      image: 'Dockerfile'
+    # runs-on: ubuntu-latest
+    #
+    # strategy:
+    #   matrix:
+    #     ruby-version: [ '2.7.0' ]
+    #
+    # steps:
+    # - uses: actions/checkout@v2
+    # - name: Set up Ruby
+    #   uses: ruby/setup-ruby@v1
+    #   with:
+    #     ruby-version: ${{ matrix.ruby-version }}
+    #
+    # - uses: actions/cache@v1
+    #   with:
+    #     path: vendor/bundle
+    #     key: gems-${{ runner.os }}-${{ matrix.ruby-version }}-${{ hashFiles('**/Gemfile.lock') }}
+    #
+    # # - run: gem update --system 3.4.22
+    # - run: sudo apt-get install -y --no-install-recommends build-essential
+    # - run: gem install bundler -v 2.4.22
+    #
+    # - run: bundle config set deployment 'true'
+    # - run: bundle config build.nokogiri --use-system-libraries
+    # - run: bundle install
+    #
+    # - run: bundle exec middleman build
diff --git a/Dockerfile b/Dockerfile
index 33b80ca..5777f8e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.6-slim
+FROM ruby:2.7-slim
 
 WORKDIR /srv/slate
 
@@ -11,7 +11,7 @@ RUN apt-get update \
     && apt-get install -y --no-install-recommends \
         build-essential \
         nodejs \
-    && gem install bundler \
+    && gem install bundler -v 2.4.22\
     && bundle install \
     && apt-get remove -y build-essential \
     && apt-get autoremove -y \
diff --git a/lib/toc_data.rb b/lib/toc_data.rb
index 4a04efe..924a6e9 100644
--- a/lib/toc_data.rb
+++ b/lib/toc_data.rb
@@ -29,3 +29,4 @@ def toc_data(page_content)
   end
   headers
 end
+
diff --git a/source/includes/_intro.md.erb b/source/includes/_intro.md.erb
index 7856759..e546435 100644
--- a/source/includes/_intro.md.erb
+++ b/source/includes/_intro.md.erb
@@ -10,4 +10,3 @@ We provide examples as:
 - Javascript (web)
 - Swift (iOS)
 - Kotlin (Android)
-