diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5ef3fe8..93e2dd6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,13 +36,13 @@ jobs:
       - name: Setup Ruby
         uses: actions/setup-ruby@v1
         with:
-          ruby-version: 2.6.x
+          ruby-version: 2.7
 
       - name: Bundle Caching
         uses: actions/cache@v2
         with:
           path: ${{ env.GEMS_PATH }}
-          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile') }}
+          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}
           restore-keys: |
             ${{ runner.os }}-gems-
 
diff --git a/.github/workflows/pages-deploy.yml.hook b/.github/workflows/pages-deploy.yml.hook
index 77aa297..4a57ea5 100644
--- a/.github/workflows/pages-deploy.yml.hook
+++ b/.github/workflows/pages-deploy.yml.hook
@@ -25,13 +25,13 @@ jobs:
       - name: Setup Ruby
         uses: actions/setup-ruby@v1
         with:
-          ruby-version: 2.6.x
+          ruby-version: 2.7
 
       - name: Bundle Caching
         uses: actions/cache@v2
         with:
           path: ${{ env.GEMS_PATH }}
-          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile') }}
+          key: ${{ runner.os }}-gems-${{ hashFiles('**/Gemfile.lock') }}
           restore-keys: |
             ${{ runner.os }}-gems-
 
@@ -65,7 +65,7 @@ jobs:
           else
             bash tools/test.sh
           fi
-          
+
       - name: Deploy
         run: |
           bash tools/deploy.sh
diff --git a/.gitignore b/.gitignore
index a76e045..ed798ee 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,7 +2,6 @@
 .*
 !.github
 
-# jekyll cache 
+# jekyll cache
 _site
-Gemfile.lock
 vendor
diff --git a/Gemfile b/Gemfile
index 8a8821c..db23cc8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,13 +6,13 @@ gem "jekyll", ">= 3.8.6", "< 5.0"
 group :jekyll_plugins do
   gem "jekyll-paginate"
   gem "jekyll-redirect-from"
-  gem "jekyll-seo-tag", "~> 2.6.1"
+  gem "jekyll-seo-tag"
   gem "jekyll-archives"
   gem "jekyll-sitemap"
 end
 
 group :test do
-  gem "html-proofer", "~> 3.16.0"
+  gem "html-proofer"
 end
 
 # Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem
diff --git a/Gemfile.lock b/Gemfile.lock
new file mode 100644
index 0000000..89d2f1e
--- /dev/null
+++ b/Gemfile.lock
@@ -0,0 +1,111 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
+    colorator (1.1.0)
+    concurrent-ruby (1.1.7)
+    em-websocket (0.5.2)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    ethon (0.12.0)
+      ffi (>= 1.3.0)
+    eventmachine (1.2.7)
+    ffi (1.13.1)
+    forwardable-extended (2.6.0)
+    html-proofer (3.17.4)
+      addressable (~> 2.3)
+      mercenary (~> 0.3)
+      nokogumbo (~> 2.0)
+      parallel (~> 1.3)
+      rainbow (~> 3.0)
+      typhoeus (~> 1.3)
+      yell (~> 2.0)
+    http_parser.rb (0.6.0)
+    i18n (1.8.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (4.1.1)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 1.0)
+      jekyll-sass-converter (~> 2.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 2.1)
+      kramdown-parser-gfm (~> 1.0)
+      liquid (~> 4.0)
+      mercenary (~> 0.4.0)
+      pathutil (~> 0.9)
+      rouge (~> 3.0)
+      safe_yaml (~> 1.0)
+      terminal-table (~> 1.8)
+    jekyll-archives (2.2.1)
+      jekyll (>= 3.6, < 5.0)
+    jekyll-paginate (1.1.0)
+    jekyll-redirect-from (0.16.0)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-sass-converter (2.1.0)
+      sassc (> 2.0.1, < 3.0)
+    jekyll-seo-tag (2.7.1)
+      jekyll (>= 3.8, < 5.0)
+    jekyll-sitemap (1.4.0)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    kramdown (2.3.0)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
+    listen (3.3.3)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.4.0)
+    mini_portile2 (2.4.0)
+    nokogiri (1.10.10)
+      mini_portile2 (~> 2.4.0)
+    nokogumbo (2.0.4)
+      nokogiri (~> 1.8, >= 1.8.4)
+    parallel (1.20.1)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (4.0.6)
+    rainbow (3.0.0)
+    rb-fsevent (0.10.4)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.4)
+    rouge (3.25.0)
+    safe_yaml (1.0.5)
+    sassc (2.4.0)
+      ffi (~> 1.9)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    thread_safe (0.3.6)
+    typhoeus (1.4.0)
+      ethon (>= 0.9.0)
+    tzinfo (1.2.8)
+      thread_safe (~> 0.1)
+    tzinfo-data (1.2020.4)
+      tzinfo (>= 1.0.0)
+    unicode-display_width (1.7.0)
+    wdm (0.1.1)
+    yell (2.2.2)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  html-proofer
+  jekyll (>= 3.8.6, < 5.0)
+  jekyll-archives
+  jekyll-paginate
+  jekyll-redirect-from
+  jekyll-seo-tag
+  jekyll-sitemap
+  tzinfo (~> 1.2)
+  tzinfo-data
+  wdm (~> 0.1.1)
+
+BUNDLED WITH
+   2.1.4
diff --git a/tools/deploy.sh b/tools/deploy.sh
index bdc6cd1..0a6353d 100755
--- a/tools/deploy.sh
+++ b/tools/deploy.sh
@@ -15,6 +15,16 @@ _no_branch=false
 _backup_dir="$(mktemp -d)"
 
 init() {
+  if [[ -z ${GITHUB_ACTION+x} ]]; then
+    echo "ERROR: This script is not allowed to run outside of GitHub Action."
+    exit -1
+  fi
+
+  # Gemfile could be changed by `bundle install` in actions workflow
+  if [[ -n $(git status Gemfile.lock --porcelain) ]]; then
+    git checkout -- Gemfile.lock
+  fi
+
   if [[ -z $(git branch -av | grep "$PAGES_BRANCH") ]]; then
     _no_branch=true
     git checkout -b "$PAGES_BRANCH"