Add PostCSS setup with required dependencies and Jekyll plugin

Author: liberaldev

Gemfile

@@ -14,3 +14,7 @@ gem "validate-website", "~> 1.6"
 # Jekyll need them for Ruby 3.4+
 gem "csv"
 gem "base64"
+
+group :jekyll_plugins do
+  gem 'jekyll-postcss-v2'
+end

Gemfile.lock

@@ -94,6 +94,7 @@ GEM
       safe_yaml (~> 1.0)
       terminal-table (>= 1.8, < 4.0)
       webrick (~> 1.7)
+    jekyll-postcss-v2 (1.0.2)
     jekyll-sass-converter (3.1.0)
       sass-embedded (~> 1.75)
     jekyll-watch (2.2.1)
@@ -245,6 +246,7 @@ DEPENDENCIES
   csv
   html-proofer
   jekyll
+  jekyll-postcss-v2
   minitest
   rake
   rouge
@@ -292,6 +294,7 @@ CHECKSUMS
   i18n (1.14.7) sha256=ceba573f8138ff2c0915427f1fc5bdf4aa3ab8ae88c8ce255eb3ecf0a11a5d0f
   io-event (1.10.0) sha256=e4e1f5bf01a1a8b8484db3c5d99b431eb3609dbc988b96622d14d77993e0e9dc
   jekyll (4.4.1) sha256=4c1144d857a5b2b80d45b8cf5138289579a9f8136aadfa6dd684b31fe2bc18c1
+  jekyll-postcss-v2 (1.0.2) sha256=f179d3de83918ebb266ac8adc3191e422107fec5b088cb1c35fa9ff9c50b89c3
   jekyll-sass-converter (3.1.0) sha256=83925d84f1d134410c11d0c6643b0093e82e3a3cf127e90757a85294a3862443
   jekyll-watch (2.2.1) sha256=bc44ed43f5e0a552836245a54dbff3ea7421ecc2856707e8a1ee203a8387a7e1
   json (2.10.2) sha256=34e0eada93022b2a0a3345bb0b5efddb6e9ff5be7c48e409cfb54ff8a36a8b06

package.json

@@ -8,6 +8,9 @@
   },
   "devDependencies": {
     "@tailwindcss/typography": "^0.5.19",
+    "autoprefixer": "^10.4.23",
+    "postcss": "^8.5.6",
+    "postcss-cli": "^11.0.1",
     "tailwindcss": "^3.4.14"
   }
 }