Switch to tailwindcss-ruby external pipeline

Replace middleman-tailwind with tailwindcss-ruby and run Tailwind
via an external_pipeline in config.rb. Add 'ostruct' for Ruby 4.0+.
Remove the checked-in compiled site.css and tailwind.config.js and
ignore source/stylesheets/site.css.

Author: thibaudgg

.gitignore

@@ -3,3 +3,4 @@
 .DS_Store
 build/
 .tmp/
+source/stylesheets/site.css

Gemfile

@@ -1,9 +1,11 @@
 source 'https://rubygems.org'
 
+gem 'ostruct' # Required for Ruby 4.0+
+
 gem 'middleman'
 gem 'middleman-favicon-maker'
 
 gem 'middleman-inline_svg'
 gem 'middleman-livereload'
 gem 'middleman-robots'
-gem 'middleman-tailwind', github: 'teaforthecat/middleman-tailwind', branch: 'upgrade-execs-to-3.4.1'
+gem 'tailwindcss-ruby'

Gemfile.lock

@@ -1,11 +1,3 @@
-GIT
-  remote: https://github.com/teaforthecat/middleman-tailwind.git
-  revision: bd6452cd9ed79a821943ef35e8f8e866ca2bc6eb
-  branch: upgrade-execs-to-3.4.1
-  specs:
-    middleman-tailwind (1.1.0)
-      middleman-core (>= 4.0.0)
-
 GEM
   remote: https://rubygems.org/
   specs:
@@ -119,6 +111,7 @@ GEM
     nokogiri (1.19.0)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
+    ostruct (0.6.3)
     padrino-helpers (0.15.3)
       i18n (>= 0.6.7, < 2)
       padrino-support (= 0.15.3)
@@ -142,6 +135,8 @@ GEM
       ffi (~> 1.9)
     securerandom (0.4.1)
     servolux (0.13.0)
+    tailwindcss-ruby (4.1.18)
+    tailwindcss-ruby (4.1.18-arm64-darwin)
     temple (0.10.4)
     thor (1.5.0)
     tilt (2.7.0)
@@ -155,6 +150,7 @@ GEM
     webrick (1.9.2)
 
 PLATFORMS
+  arm64-darwin-25
   ruby
 
 DEPENDENCIES
@@ -163,7 +159,8 @@ DEPENDENCIES
   middleman-inline_svg
   middleman-livereload
   middleman-robots
-  middleman-tailwind!
+  ostruct
+  tailwindcss-ruby
 
 BUNDLED WITH
    2.7.2

config.rb

@@ -5,11 +5,11 @@
 # https://middlemanapp.com/advanced/configuration/#environment-specific-settings
 set :url_root, @app.data.site.host
 
-activate :tailwind do |config|
-  config.destination_path = 'source/stylesheets/site.css'
-  config.css_path = 'source/stylesheets/tailwind.css'
-  config.config_path = 'tailwind.config.js'
-end
+activate :external_pipeline,
+         name: :tailwindcss,
+         command: build? ? 'tailwindcss -i source/stylesheets/tailwind.css -o source/stylesheets/site.css --minify' : 'tailwindcss -i source/stylesheets/tailwind.css -o source/stylesheets/site.css --watch',
+         source: 'source',
+         latency: 1
 activate :livereload
 activate :i18n,
          mount_at_root: :en,