diff --git a/.github/workflows/ci-master.yml b/.github/workflows/ci-master.yml
index 0be2958..b2ca55f 100644
--- a/.github/workflows/ci-master.yml
+++ b/.github/workflows/ci-master.yml
@@ -1,45 +1,108 @@
-on: 
+on:
   push:
     branches:
-    - master
+      - master
+  pull_request:
+    branches:
+      - master
 
-name: Master branch CI
+name: CI
 
 jobs:
+  jekyll-build:
+    name: Build (jekyll gem)
+    strategy:
+      fail-fast: false
+      matrix:
+        jekyll-version: [3.9, 4.3]
+        os: [ ubuntu-latest, macos-latest, windows-latest ]
+        ruby-version: ["3.0", "3.1", "3.2"]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@v4
+    - name: Setup Ruby ${{ matrix.ruby-version }}
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby-version }}
+        bundler-cache: false
+    - name: Bundle Install (Jekyll ${{ matrix.jekyll-version }})
+      run: bundle install
+      env:
+        BUNDLE_GEMFILE: fixtures/Gemfile-jekyll-${{ matrix.jekyll-version }}
+    - name: Init Search
+      run: bundle exec rake search:init
+      env:
+        BUNDLE_GEMFILE: fixtures/Gemfile-jekyll-${{ matrix.jekyll-version }}
+    - name: Build Site
+      run: bundle exec jekyll build
+      env:
+        BUNDLE_GEMFILE: fixtures/Gemfile-jekyll-${{ matrix.jekyll-version }}
 
-  jekyll-latest:
-    name: Build Jekyll site (latest)
+  github-pages-build:
+    name: Build (github-pages gem)
     runs-on: ubuntu-latest
     steps:
+    - uses: actions/checkout@v4
+    - name: Setup Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: "3.2"
+        bundler-cache: false
+    - name: Bundle Install
+      run: bundle install
+      env:
+        BUNDLE_GEMFILE: fixtures/Gemfile-github-pages
+    - name: Build Site
+      run: bundle exec jekyll build
+      env:
+        BUNDLE_GEMFILE: fixtures/Gemfile-github-pages
 
-    - uses: actions/checkout@master
-
-    - name: Build the site in the jekyll/builder container
-      run: |
-        docker run --rm \
-        --volume="${{ github.workspace }}:/srv/jekyll" \
-        jekyll/builder:latest /bin/bash -c "gem install bundler && git config --global --add safe.directory /srv/jekyll && chmod -R 777 /srv/jekyll && jekyll build && bundle exec just-the-docs rake search:init"
-  jekyll-3-8-5:
-    name: Build Jekyll site (v3.8.5)
+  validate:
+    name: Validate HTML
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby-version: ["3.2"]
     runs-on: ubuntu-latest
-    steps:
 
-    - uses: actions/checkout@master
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Ruby ${{ matrix.ruby-version }}
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+          cache-version: 0 # Increment this number if you need to re-download cached gems
+      - name: Cache HTMLProofer
+        id: cache-htmlproofer
+        uses: actions/cache@v3
+        with:
+          path: tmp/.htmlproofer
+          key: ${{ runner.os }}-htmlproofer
+      - name: Build Site
+        run: bundle exec jekyll build
+      - name: Test with Nu Validator
+        uses: Cyb3r-Jak3/html5validator-action@2a593a9f2c10593cbac84791a6fc4c47e9a106c8
+        with:
+          config: fixtures/html5validator-config.yml
+      - name: Test with html-proofer
+        run: bundle exec htmlproofer _site --ignore-urls "/github.com/,/web.archive.org/"
+        env:
+          NOKOGIRI_USE_SYSTEM_LIBRARIES: true
 
-    - name: Build the site in the jekyll/builder container
-      run: |
-        docker run --rm \
-        --volume="${{ github.workspace }}:/srv/jekyll" \
-        jekyll/builder:3.8.5 /bin/bash -c "gem install bundler && chmod -R 777 /srv/jekyll && jekyll build && bundle exec just-the-docs rake search:init"
   assets:
-    name: Format and test CSS and JS
+    name: Test CSS and JS
     runs-on: ubuntu-latest
 
+    strategy:
+      matrix:
+        node-version: [18.x]
+
     steps:
-    - uses: actions/checkout@v2
-    - name: Use Node.js 12.x
-      uses: actions/setup-node@v1
+    - uses: actions/checkout@v4
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v3
       with:
-        node-version: '12.x'
+        node-version: ${{ matrix.node-version }}
     - run: npm install
-    - run: npm test
+    - run: npm test
\ No newline at end of file