Bootstrap v4 dark mode for modals and settings window (#1650)

* Bootstrap v4 dark mode for modals and settings window

* Fix package-lock.json

* Fix package-lock.json again

* Merge'd

* Oops

* Refactor into helper

webpack.config.renderer.js

@@ -100,10 +100,22 @@ module.exports = merge(base, {
             },
         }, {
             test: /\.css$/,
+            exclude: /\.lazy\.css$/,
             use: [
                 MiniCssExtractPlugin.loader,
                 'css-loader',
             ],
+        }, {
+            test: /\.lazy\.css$/,
+            use: [
+                {
+                    loader: 'style-loader',
+                    options: {
+                        injectType: 'lazyStyleTag',
+                    },
+                },
+                'css-loader',
+            ],
         }, {
             test: /\.scss$/,
             use: [