Add css minify

package.json

@@ -5,9 +5,12 @@
     "build:bookmarklet": "echo -n 'javascript:' > ./examples/bookmarklet/source-min.js && cat ./tmp/source-cdn-min.js >> ./examples/bookmarklet/source-min.js",
     "build:apache-cdn": "OUT=./examples/apache-directory-list/header.html; echo -n '<script type=\"text/javascript\">' > $OUT && cat ./tmp/source-cdn-min.js >> $OUT && echo -n '</script><!--' >> $OUT",
     "build:apache-local": "OUT=./examples/apache-directory-list-local/header.html; echo -n '<script type=\"text/javascript\">' > $OUT && cat ./tmp/source-local-min.js >> $OUT && echo -n '</script><!--' >> $OUT",
-    "build": "npm run build:pp && npm run build:uglify && npm run build:bookmarklet && npm run build:apache-cdn && npm run build:apache-local"
+    "build:cleancss": "cleancss -o ./assets/css/style-min.css ./assets/css/style.css",
+    "build": "npm run build:cleancss && npm run build:pp && npm run build:uglify && npm run build:bookmarklet && npm run build:apache-cdn && npm run build:apache-local"
   },
   "devDependencies": {
+    "clean-css": "^4.2.1",
+    "clean-css-cli": "^4.2.1",
     "preprocessor": "1.4.0",
     "uglify-js": "^3.4.9"
   }