Минимизация css, корректировка правил, хеширование файлов, настройки сборок (#6)

package.json

@@ -31,6 +31,7 @@
     "babel-loader": "^8.1.0",
     "clean-webpack-plugin": "^3.0.0",
     "css-loader": "^3.6.0",
+    "cssnano": "^4.1.10",
     "eslint": "^7.4.0",
     "eslint-loader": "^4.0.2",
     "file-loader": "^6.0.0",
@@ -39,6 +40,9 @@
     "image-webpack-loader": "^6.0.0",
     "jsdoc": "^3.6.4",
     "mini-css-extract-plugin": "^0.9.0",
+    "postcss-import": "^12.0.1",
+    "postcss-loader": "^3.0.0",
+    "postcss-preset-env": "^6.7.0",
     "url-loader": "^4.1.0",
     "webpack": "^4.43.0",
     "webpack-cli": "^3.3.12",