diff --git a/Gemfile b/Gemfile
index 778e82e8..fc892603 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,8 @@
 source "https://rubygems.org"
 
-gem "jekyll"
-gem "unindent"
-gem 'github-pages', github: 'github/pages-gem'
+# keep versions up-to-date with the actual GitHub Pages setup
+# https://pages.github.com/versions/
+
+# just do `bundle update` to get the latest version.
+
+gem 'github-pages'
diff --git a/Gemfile.lock b/Gemfile.lock
index 7cfa2cb7..686123da 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,70 +1,126 @@
-GIT
-  remote: git://github.com/github/pages-gem.git
-  revision: a73cbe4d6b683e0ef1bbeefc01e10daac1498a65
-  specs:
-    github-pages (12)
-      RedCloth (= 4.2.9)
-      jekyll (= 1.4.2)
-      kramdown (= 1.2.0)
-      liquid (= 2.5.4)
-      maruku (= 0.7.0)
-      rdiscount (= 2.1.7)
-      redcarpet (= 2.3.0)
-
 GEM
   remote: https://rubygems.org/
   specs:
     RedCloth (4.2.9)
+    activesupport (4.2.0)
+      i18n (~> 0.7)
+      json (~> 1.7, >= 1.7.7)
+      minitest (~> 5.1)
+      thread_safe (~> 0.3, >= 0.3.4)
+      tzinfo (~> 1.1)
     blankslate (2.1.2.4)
-    classifier (1.3.4)
-      fast-stemmer (>= 1.0.0)
+    celluloid (0.16.0)
+      timers (~> 4.0.0)
+    classifier-reborn (2.0.3)
+      fast-stemmer (~> 1.0)
+    coffee-script (2.3.0)
+      coffee-script-source
+      execjs
+    coffee-script-source (1.8.0)
     colorator (0.1)
-    commander (4.1.5)
-      highline (~> 1.6.11)
+    execjs (2.2.2)
     fast-stemmer (1.0.2)
-    ffi (1.9.3)
-    highline (1.6.20)
-    jekyll (1.4.2)
-      classifier (~> 1.3)
+    ffi (1.9.6)
+    gemoji (2.1.0)
+    github-pages (32)
+      RedCloth (= 4.2.9)
+      github-pages-health-check (~> 0.2)
+      jekyll (= 2.4.0)
+      jekyll-coffeescript (= 1.0.1)
+      jekyll-mentions (= 0.2.1)
+      jekyll-redirect-from (= 0.6.2)
+      jekyll-sass-converter (= 1.2.0)
+      jekyll-sitemap (= 0.6.3)
+      jemoji (= 0.4.0)
+      kramdown (= 1.5.0)
+      liquid (= 2.6.1)
+      maruku (= 0.7.0)
+      mercenary (~> 0.3)
+      pygments.rb (= 0.6.0)
+      rdiscount (= 2.1.7)
+      redcarpet (= 3.1.2)
+      terminal-table (~> 1.4)
+    github-pages-health-check (0.2.1)
+      net-dns (~> 0.6)
+      public_suffix (~> 1.4)
+    hitimes (1.2.2)
+    html-pipeline (1.9.0)
+      activesupport (>= 2)
+      nokogiri (~> 1.4)
+    i18n (0.7.0)
+    jekyll (2.4.0)
+      classifier-reborn (~> 2.0)
       colorator (~> 0.1)
-      commander (~> 4.1.3)
-      liquid (~> 2.5.2)
-      listen (~> 1.3)
-      maruku (~> 0.7.0)
-      pygments.rb (~> 0.5.0)
-      redcarpet (~> 2.3.0)
-      safe_yaml (~> 0.9.7)
+      jekyll-coffeescript (~> 1.0)
+      jekyll-gist (~> 1.0)
+      jekyll-paginate (~> 1.0)
+      jekyll-sass-converter (~> 1.0)
+      jekyll-watch (~> 1.1)
+      kramdown (~> 1.3)
+      liquid (~> 2.6.1)
+      mercenary (~> 0.3.3)
+      pygments.rb (~> 0.6.0)
+      redcarpet (~> 3.1)
+      safe_yaml (~> 1.0)
       toml (~> 0.1.0)
-    kramdown (1.2.0)
-    liquid (2.5.4)
-    listen (1.3.1)
+    jekyll-coffeescript (1.0.1)
+      coffee-script (~> 2.2)
+    jekyll-gist (1.1.0)
+    jekyll-mentions (0.2.1)
+      html-pipeline (~> 1.9.0)
+      jekyll (~> 2.0)
+    jekyll-paginate (1.1.0)
+    jekyll-redirect-from (0.6.2)
+      jekyll (~> 2.0)
+    jekyll-sass-converter (1.2.0)
+      sass (~> 3.2)
+    jekyll-sitemap (0.6.3)
+    jekyll-watch (1.2.0)
+      listen (~> 2.7)
+    jemoji (0.4.0)
+      gemoji (~> 2.0)
+      html-pipeline (~> 1.9)
+      jekyll (~> 2.0)
+    json (1.8.2)
+    kramdown (1.5.0)
+    liquid (2.6.1)
+    listen (2.8.5)
+      celluloid (>= 0.15.2)
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9)
-      rb-kqueue (>= 0.2)
     maruku (0.7.0)
+    mercenary (0.3.5)
+    mini_portile (0.6.2)
+    minitest (5.5.1)
+    net-dns (0.8.0)
+    nokogiri (1.6.5)
+      mini_portile (~> 0.6.0)
     parslet (1.5.0)
       blankslate (~> 2.0)
-    posix-spawn (0.3.8)
-    pygments.rb (0.5.4)
+    posix-spawn (0.3.9)
+    public_suffix (1.4.6)
+    pygments.rb (0.6.0)
       posix-spawn (~> 0.3.6)
       yajl-ruby (~> 1.1.0)
     rb-fsevent (0.9.4)
-    rb-inotify (0.9.3)
-      ffi (>= 0.5.0)
-    rb-kqueue (0.2.0)
+    rb-inotify (0.9.5)
       ffi (>= 0.5.0)
     rdiscount (2.1.7)
-    redcarpet (2.3.0)
-    safe_yaml (0.9.7)
-    toml (0.1.0)
+    redcarpet (3.1.2)
+    safe_yaml (1.0.4)
+    sass (3.4.10)
+    terminal-table (1.4.5)
+    thread_safe (0.3.4)
+    timers (4.0.1)
+      hitimes
+    toml (0.1.2)
       parslet (~> 1.5.0)
-    unindent (1.0)
+    tzinfo (1.2.2)
+      thread_safe (~> 0.1)
     yajl-ruby (1.1.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  github-pages!
-  jekyll
-  unindent
+  github-pages