diff --git a/Gemfile b/Gemfile
index c30e8cf..6f3fe65 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,6 @@
 source 'https://rubygems.org'
 
-gem 'jekyll'
-gem 'kramdown'
+# use the versions in https://pages.github.com/versions.json
+gem 'jekyll', '3.10.0'
+gem 'kramdown', '2.4.0'
+gem 'kramdown-parser-gfm', '1.1.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 85a2bd0..9eac0dc 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,39 +3,35 @@ GEM
   specs:
     addressable (2.8.7)
       public_suffix (>= 2.0.2, < 7.0)
-    bigdecimal (3.1.8)
     colorator (1.1.0)
     concurrent-ruby (1.3.4)
+    csv (3.3.0)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
     eventmachine (1.2.7)
     ffi (1.17.0)
     forwardable-extended (2.6.0)
-    google-protobuf (4.28.2)
-      bigdecimal
-      rake (>= 13)
     http_parser.rb (0.8.0)
     i18n (1.14.6)
       concurrent-ruby (~> 1.0)
-    jekyll (4.3.4)
+    jekyll (3.10.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
+      csv (~> 3.0)
       em-websocket (~> 0.5)
-      i18n (~> 1.0)
-      jekyll-sass-converter (>= 2.0, < 4.0)
+      i18n (>= 0.7, < 2)
+      jekyll-sass-converter (~> 1.0)
       jekyll-watch (~> 2.0)
-      kramdown (~> 2.3, >= 2.3.1)
-      kramdown-parser-gfm (~> 1.0)
+      kramdown (>= 1.17, < 3)
       liquid (~> 4.0)
-      mercenary (>= 0.3.6, < 0.5)
+      mercenary (~> 0.3.3)
       pathutil (~> 0.9)
-      rouge (>= 3.0, < 5.0)
+      rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
-      terminal-table (>= 1.8, < 4.0)
-      webrick (~> 1.7)
-    jekyll-sass-converter (3.0.0)
-      sass-embedded (~> 1.54)
+      webrick (>= 1.0)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     kramdown (2.4.0)
@@ -46,31 +42,30 @@ GEM
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    mercenary (0.4.0)
+    mercenary (0.3.6)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (6.0.1)
-    rake (13.2.1)
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
     rexml (3.3.7)
-    rouge (4.4.0)
+    rouge (3.30.0)
     safe_yaml (1.0.5)
-    sass-embedded (1.79.3)
-      google-protobuf (~> 4.27)
-      rake (>= 13)
-    terminal-table (3.0.2)
-      unicode-display_width (>= 1.1.1, < 3)
-    unicode-display_width (2.6.0)
+    sass (3.7.4)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
     webrick (1.8.2)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  jekyll
-  kramdown
+  jekyll (= 3.10.0)
+  kramdown (= 2.4.0)
+  kramdown-parser-gfm (= 1.1.0)
 
 BUNDLED WITH
    2.5.3