diff --git a/Gemfile b/Gemfile
index fc4dd9e2..5b338482 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,9 @@
 source 'https://rubygems.org'
 
-gem 'govuk_tech_docs', '~> 3.5.0'
-gem 'haml', '~> 5.2', '>= 5.2.2'
+gem 'liquid'
+gem 'slim'
+gem 'therubyracer'
+gem 'less'
+gem 'govuk_tech_docs', '~> 4.0'
+gem "haml", "~> 6.0"
 gem 'html-proofer'
diff --git a/Gemfile.lock b/Gemfile.lock
index 5bfcd515..f9d4c0b3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,22 +1,25 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (7.0.8.1)
+    activesupport (7.0.8.5)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
       tzinfo (~> 2.0)
     addressable (2.8.4)
       public_suffix (>= 2.0.2, < 6.0)
-    autoprefixer-rails (10.4.16.0)
+    autoprefixer-rails (10.4.19.0)
       execjs (~> 2)
-    backports (3.24.1)
+    backports (3.25.0)
+    base64 (0.2.0)
+    bigdecimal (3.1.8)
     chronic (0.10.2)
     chunky_png (1.4.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
     coffee-script-source (1.12.2)
+    commonjs (0.2.7)
     commonmarker (0.23.10)
     compass (1.0.3)
       chunky_png (~> 1.2)
@@ -30,9 +33,10 @@ GEM
       sass (>= 3.3.0, < 3.5)
     compass-import-once (1.0.5)
       sass (>= 3.2, < 3.5)
-    concurrent-ruby (1.2.3)
+    concurrent-ruby (1.3.4)
     contracts (0.16.1)
-    dotenv (3.1.0)
+    csv (3.3.0)
+    dotenv (3.1.4)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
@@ -40,26 +44,36 @@ GEM
     ethon (0.15.0)
       ffi (>= 1.15.0)
     eventmachine (1.2.7)
-    execjs (2.9.1)
+    execjs (2.10.0)
     fast_blank (1.0.1)
-    fastimage (2.3.0)
+    fastimage (2.3.1)
     ffi (1.15.5)
-    govuk_tech_docs (3.5.0)
+    google-protobuf (4.28.2)
+      bigdecimal
+      rake (>= 13)
+    govuk_tech_docs (4.0.0)
       autoprefixer-rails (~> 10.2)
+      base64
+      bigdecimal
       chronic (~> 0.10.2)
-      haml (< 6.0.0)
+      csv
+      haml (~> 6.0)
       middleman (~> 4.0)
-      middleman-autoprefixer (~> 2.10.0)
-      middleman-compass (>= 4.0.0)
+      middleman-autoprefixer (~> 2.10)
+      middleman-compass (~> 4.0)
       middleman-livereload
       middleman-search-gds
       middleman-sprockets (~> 4.0.0)
-      middleman-syntax (~> 3.2.0)
+      middleman-syntax (~> 3.4)
+      mutex_m
       nokogiri
       openapi3_parser (~> 0.9.0)
-      redcarpet (~> 3.5.1)
-    haml (5.2.2)
-      temple (>= 0.8.0)
+      redcarpet (~> 3.6)
+      sassc-embedded (~> 1.78.0)
+      terser (~> 1.2.3)
+    haml (6.3.0)
+      temple (>= 0.8.2)
+      thor
       tilt
     hamster (3.0.0)
       concurrent-ruby (~> 1.0)
@@ -77,6 +91,10 @@ GEM
       concurrent-ruby (~> 1.0)
     kramdown (2.4.0)
       rexml
+    less (2.6.0)
+      commonjs (~> 0.2.7)
+    libv8 (3.16.14.19.1)
+    liquid (5.5.1)
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
@@ -132,12 +150,13 @@ GEM
     middleman-sprockets (4.0.0)
       middleman-core (~> 4.0)
       sprockets (>= 3.0)
-    middleman-syntax (3.2.0)
+    middleman-syntax (3.4.0)
       middleman-core (>= 3.2)
       rouge (~> 3.2)
     mini_portile2 (2.8.6)
-    minitest (5.22.2)
+    minitest (5.25.1)
     multi_json (1.15.0)
+    mutex_m (0.2.0)
     nokogiri (1.16.5)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
@@ -152,26 +171,39 @@ GEM
     parslet (2.0.0)
     public_suffix (5.0.1)
     racc (1.7.3)
-    rack (2.2.8.1)
+    rack (2.2.10)
     rack-livereload (0.3.17)
       rack
     rainbow (3.1.1)
+    rake (13.2.1)
     rb-fsevent (0.11.2)
-    rb-inotify (0.10.1)
+    rb-inotify (0.11.1)
       ffi (~> 1.0)
-    redcarpet (3.5.1)
-    rexml (3.3.6)
-      strscan
+    redcarpet (3.6.0)
+    ref (2.0.0)
+    rexml (3.3.8)
     rouge (3.30.0)
     sass (3.4.25)
+    sass-embedded (1.80.3)
+      google-protobuf (~> 4.28)
+      rake (>= 13)
     sassc (2.4.0)
       ffi (~> 1.9)
+    sassc-embedded (1.78.0)
+      sass-embedded (~> 1.78)
     servolux (0.13.0)
+    slim (5.1.0)
+      temple (~> 0.10.0)
+      tilt (>= 2.0.6, < 2.2)
     sprockets (4.2.1)
       concurrent-ruby (~> 1.0)
       rack (>= 2.2.4, < 4)
-    strscan (3.1.0)
-    temple (0.10.2)
+    temple (0.10.3)
+    terser (1.2.4)
+      execjs (>= 0.3.0, < 3)
+    therubyracer (0.12.3)
+      libv8 (~> 3.16.14.15)
+      ref
     thor (1.2.2)
     tilt (2.0.11)
     toml (0.3.0)
@@ -182,16 +214,20 @@ GEM
       concurrent-ruby (~> 1.0)
     uglifier (3.2.0)
       execjs (>= 0.3.0, < 3)
-    webrick (1.8.1)
+    webrick (1.8.2)
     yell (2.2.2)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  govuk_tech_docs (~> 3.5.0)
-  haml (~> 5.2, >= 5.2.2)
+  govuk_tech_docs (~> 4.0)
+  haml (~> 6.0)
   html-proofer
+  less
+  liquid
+  slim
+  therubyracer
 
 BUNDLED WITH
    2.1.4
diff --git a/source/javascripts/govuk_frontend.js b/source/javascripts/govuk_frontend.js
new file mode 100644
index 00000000..c3588dfe
--- /dev/null
+++ b/source/javascripts/govuk_frontend.js
@@ -0,0 +1 @@
+//= require govuk_frontend_all