diff --git a/Gemfile b/Gemfile
index 91a5da3..14c58a3 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ gem 'typogruby'         # text enhancements
 gem 'rouge'             # syntax highlighting
 gem 'slim'              # templates
 gem 'builder'           # xml sitemaps
-gem 'yuicompressor'     # css/js uglifying
+gem 'terser'            # js uglifying
 gem 'ruby-xxHash'       # for cache busting
 
 group :nanoc do
diff --git a/Gemfile.lock b/Gemfile.lock
index 5bbe64b..7851cb5 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -25,6 +25,7 @@ GEM
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
     eventmachine (1.2.7)
+    execjs (2.9.1)
     ffi (1.16.3)
     google-protobuf (3.25.3-x86_64-linux)
     http_parser.rb (0.8.0)
@@ -126,6 +127,8 @@ GEM
       set (~> 1.0)
     stringio (3.1.0)
     temple (0.10.3)
+    terser (1.2.2)
+      execjs (>= 0.3.0, < 3)
     tilt (2.3.0)
     tty-color (0.6.0)
     tty-command (0.10.1)
@@ -139,7 +142,6 @@ GEM
       nokogiri (~> 1.6)
       rexml (~> 3.2)
     webrick (1.8.1)
-    yuicompressor (1.3.3)
     zeitwerk (2.6.13)
 
 PLATFORMS
@@ -157,9 +159,9 @@ DEPENDENCIES
   rouge
   ruby-xxHash
   slim
+  terser
   typogruby
   w3c_validators
-  yuicompressor
 
 RUBY VERSION
    ruby 3.0.5p211
diff --git a/Rules b/Rules
index 965c86b..5fb49c4 100644
--- a/Rules
+++ b/Rules
@@ -1,7 +1,5 @@
 #!/usr/bin/env ruby
 
-require 'ruby-xxhash'
-
 preprocess do
   write_sitemap_file
 end
@@ -17,26 +15,25 @@ compile '/**/*.{html,md}' do
   filter :tidy if @config[:prod]
 end
 
-compile '/{css/*.scss,js/*.js}' do
-  ext = "." + item.identifier.ext
-  if ext == '.scss'
-    filter :dart_sass, {
-      :syntax => :scss,
-      :style => (@config[:prod] ? :compressed : :expanded)
-    }
-    ext = ".css"
+ignore '/css/{vendor,bits}/*'
+compile '/css/*.scss' do
+  filter :dart_sass, :style => (@config[:prod] ? :compressed : :expanded)
+end
+
+compile '/js/*.js' do
+  if @config[:prod]
+    filter :terser
   end
+end
 
-  # compress and use a hash to avoid caching issues
+route '/{js/*.js,css/*.scss}' do
+  ext = item.identifier.ext == 'scss' ? '.css' : '.' + item.identifier.ext
   if @config[:prod]
-    filter :yui_compressor, :type => :js if ext == ".js"
-    checksum = XXhash.xxh32(File.read(item[:filename]), 0xEA51)
-    write item.identifier.without_ext + '-' + checksum.to_s + ".min" + ext
+    item.identifier.without_ext + '-' + asset_hash(item) + '.min' + ext
   else
-    write item.identifier.without_ext + ext
+    item.identifier.without_ext + ext
   end
 end
-ignore '/css/**/*'
 
 compile '/sitemap.xml' do
   filter :erb
diff --git a/lib/asset_hash.rb b/lib/asset_hash.rb
new file mode 100644
index 0000000..7956724
--- /dev/null
+++ b/lib/asset_hash.rb
@@ -0,0 +1,9 @@
+
+# use a hash to avoid caching issues
+
+require 'ruby-xxhash'
+
+def asset_hash(item)
+  sum = XXhash.xxh32(File.read(@item[:filename]), 0xEA51)
+  return sum.to_s
+end