Add default postcss plugins

lib/webpack.config.js

@@ -53,12 +53,6 @@ module.exports = async function() {
     )
   }
 
-  const postCssDefault = () => [
-    require('autoprefixer')({ browsers: ['last 2 versions', 'IE 11'] })
-  ]
-
-  const postCss = themeConfig.postCss ? themeConfig.postCss : postCssDefault
-
   const extractSass = new ExtractTextPlugin({
     filename: '[name].css',
     disable: isDev
@@ -96,7 +90,25 @@ module.exports = async function() {
                 loader: 'postcss-loader',
                 options: {
                   sourceMap: isDev ? 'inline' : false,
-                  plugins: postCss
+                  plugins: loader => {
+                    const defaultPlugins = () => [
+                      require('autoprefixer')({
+                        browsers: ['last 2 versions', 'IE 11']
+                      }),
+                      require('lost'),
+                      require('postcss-custom-media'),
+                      require('postcss-zindex'),
+                      require('postcss-discard-duplicates'),
+                      require('postcss-unique-selectors')
+                    ]
+
+                    // Allow custom PostCSS configuration
+                    if (themeConfig.postCss) {
+                      return themeConfig.postCss(loader, defaultPlugins)
+                    }
+
+                    return defaultPlugins()
+                  }
                 }
               },
               {

package.json

@@ -38,10 +38,15 @@
     "file-loader": "^0.11.2",
     "find-up": "^2.1.0",
     "loglevel": "^1.4.1",
+    "lost": "^8.2.0",
     "mkdirp": "^0.5.1",
     "node-sass": "^4.5.3",
     "node-version": "^1.0.0",
+    "postcss-custom-media": "^6.0.0",
+    "postcss-discard-duplicates": "^2.1.0",
     "postcss-loader": "^2.0.6",
+    "postcss-unique-selectors": "^2.0.2",
+    "postcss-zindex": "^2.2.0",
     "rimraf": "^2.6.1",
     "sass-loader": "^6.0.6",
     "style-loader": "^0.18.2",

yarn.lock

@@ -3359,6 +3359,13 @@ loose-envify@^1.0.0:
   dependencies:
     js-tokens "^3.0.0"
 
+lost@^8.2.0:
+  version "8.2.0"
+  resolved "https://registry.yarnpkg.com/lost/-/lost-8.2.0.tgz#107d0733b286029a3587bc1230f98d2a6eb21ef7"
+  dependencies:
+    object-assign "^4.1.0"
+    postcss "^6.0.6"
+
 loud-rejection@^1.0.0:
   version "1.6.0"
   resolved "https://registry.yarnpkg.com/loud-rejection/-/loud-rejection-1.6.0.tgz#5b46f80147edee578870f086d04821cf998e551f"
@@ -4060,13 +4067,19 @@ postcss-convert-values@^2.3.4:
     postcss "^5.0.11"
     postcss-value-parser "^3.1.2"
 
+postcss-custom-media@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/postcss-custom-media/-/postcss-custom-media-6.0.0.tgz#be532784110ecb295044fb5395a18006eb21a737"
+  dependencies:
+    postcss "^6.0.1"
+
 postcss-discard-comments@^2.0.4:
   version "2.0.4"
   resolved "https://registry.yarnpkg.com/postcss-discard-comments/-/postcss-discard-comments-2.0.4.tgz#befe89fafd5b3dace5ccce51b76b81514be00e3d"
   dependencies:
     postcss "^5.0.14"
 
-postcss-discard-duplicates@^2.0.1:
+postcss-discard-duplicates@^2.0.1, postcss-discard-duplicates@^2.1.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/postcss-discard-duplicates/-/postcss-discard-duplicates-2.1.0.tgz#b9abf27b88ac188158a5eb12abcae20263b91932"
   dependencies:
@@ -4290,7 +4303,7 @@ postcss-value-parser@^3.0.1, postcss-value-parser@^3.0.2, postcss-value-parser@^
   version "3.3.0"
   resolved "https://registry.yarnpkg.com/postcss-value-parser/-/postcss-value-parser-3.3.0.tgz#87f38f9f18f774a4ab4c8a232f5c5ce8872a9d15"
 
-postcss-zindex@^2.0.1:
+postcss-zindex@^2.0.1, postcss-zindex@^2.2.0:
   version "2.2.0"
   resolved "https://registry.yarnpkg.com/postcss-zindex/-/postcss-zindex-2.2.0.tgz#d2109ddc055b91af67fc4cb3b025946639d2af22"
   dependencies:
@@ -4307,7 +4320,7 @@ postcss@^5.0.10, postcss@^5.0.11, postcss@^5.0.12, postcss@^5.0.13, postcss@^5.0
     source-map "^0.5.6"
     supports-color "^3.2.3"
 
-postcss@^6.0.1, postcss@^6.0.10, postcss@^6.0.2:
+postcss@^6.0.1, postcss@^6.0.10, postcss@^6.0.2, postcss@^6.0.6:
   version "6.0.10"
   resolved "https://registry.yarnpkg.com/postcss/-/postcss-6.0.10.tgz#c311b89734483d87a91a56dc9e53f15f4e6e84e4"
   dependencies: