Re-add custom theme integration

client/build/webpack.base.conf.js

@@ -1,7 +1,7 @@
 'use strict';
 const path = require('path');
 const config = require('../config');
-var MiniCssExtractPlugin = require('mini-css-extract-plugin')
+var MiniCssExtractPlugin = require('mini-css-extract-plugin');
 
 const {VueLoaderPlugin} = require('vue-loader');
 
@@ -40,8 +40,8 @@ module.exports = {
   },
   optimization: {
     splitChunks: {
-      chunks: 'all'
-    }
+      chunks: 'all',
+    },
   },
   resolve: {
     extensions: ['.js', '.ts', '.vue', '.json', '.gql', '.graphql', '.scss'],
@@ -123,9 +123,15 @@ module.exports = {
           isDev ? 'vue-style-loader' : MiniCssExtractPlugin.loader,
           'css-loader',
           'postcss-loader',
-          'sass-loader'
-        ]
-      }
+          {
+            loader: 'sass-loader',
+            options: {
+              additionalData: process.env.THEME ? `@import "styles/themes/_${process.env.THEME}.scss";` : '',
+              sourceMap: isDev,
+            },
+          },
+        ],
+      },
       // styleRule(false), // css rule
       // styleRule(true), // sass rule
     ],