diff --git a/build/builder.sh b/build/builder.sh
index bf0a1ea..53238a8 100644
--- a/build/builder.sh
+++ b/build/builder.sh
@@ -34,11 +34,15 @@ cp -r $agdaHtml/* code/
 # Static folder changed, re-run Hugo
 hugo $hugoFlags --config=config.toml,config-urls.toml
 
-# Output result
-mkdir $out
-cp -r public/$publicPath/* $out/
-
-# Do post-processing of HTML files: render math and link up Agda code
-htmlfiles=$(find $out/ -regex "$out/.*\.html")
+# Do post-processing of HTML files: render math, link up Agda code, subset fonts and icons
+gendir="public/$publicPath"
+htmlfiles=$(find $gendir/ -regex "$gendir/.*\.html")
+chmod -R u+w $gendir
 echo $htmlfiles | xargs ${gems}/bin/bundle exec ${ruby}/bin/ruby ./convert.rb --katex-js-file static/katex/katex.min.js
 echo $htmlfiles | xargs ${gems}/bin/bundle exec ${ruby}/bin/ruby ./agda.rb
+echo $htmlfiles | xargs ${gems}/bin/bundle exec ${ruby}/bin/ruby ./chatgpt-subset-feather-icon.rb $gendir/feather-sprite.svg
+echo $htmlfiles | xargs python3 chatgpt-subset-one-go.py $gendir
+
+# Output result
+mkdir $out
+cp -r $gendir/* $out/
diff --git a/flake.lock b/flake.lock
index 76efbcf..ef9e24c 100644
--- a/flake.lock
+++ b/flake.lock
@@ -23,11 +23,11 @@
     "blog-source": {
       "flake": false,
       "locked": {
-        "lastModified": 1735245303,
-        "narHash": "sha256-dqBLJ456fQtTwL594j3265ctqALan0PzrWreu2qpT2w=",
+        "lastModified": 1740345918,
+        "narHash": "sha256-FVG/2NXiKJAxmvQJCqzK7GVOFu/NkN/L2x0ndMDAfEk=",
         "ref": "refs/heads/master",
-        "rev": "7130c6bd1124dd048d2ede082e3502d8924b8939",
-        "revCount": 899,
+        "rev": "11be991946cb8e6d0d710077fc6478e782fdfc94",
+        "revCount": 909,
         "submodules": true,
         "type": "git",
         "url": "https://dev.danilafe.com/Web-Projects/blog-static.git"
diff --git a/lib.nix b/lib.nix
index 708ed40..8ab55b5 100644
--- a/lib.nix
+++ b/lib.nix
@@ -14,6 +14,13 @@ let
     gemset = ./gemset.nix;
   };
 
+  pythonEnv = python3.withPackages (python-pkgs: [
+    python-pkgs.beautifulsoup4
+    python-pkgs.lxml
+    python-pkgs.fonttools
+    python-pkgs.brotli
+  ]);
+
   # --- Building Agda HTML ---
   agdaEnv = agda.withPackages [ agdaPackages.standard-library ];
   agdaHtml = settings:
@@ -52,7 +59,7 @@ let
     gems = gems settings;
     agdaHtml = agdaHtml settings;
     buildInputs = [
-      hugo ruby stork agdaEnv
+      hugo ruby stork agdaEnv pythonEnv
     ];
   };
 in