Add first loaders to handle css

- Installed style-loader and css-loader
- Configured webpack.config to use both loaders on css files
- Remember the order we use them in webpack.config matters

package.json

@@ -11,6 +11,8 @@
   "author": "",
   "license": "ISC",
   "devDependencies": {
+    "css-loader": "^2.1.0",
+    "style-loader": "^0.23.1",
     "webpack": "^4.29.6",
     "webpack-cli": "^3.2.3"
   }