Added css theme based on user system preferences

.eslintrc.js

@@ -1,26 +1,27 @@
 module.exports = {
   env: {
     browser: true,
-    es2021: true
+    es2021: true,
   },
   extends: 'google',
   overrides: [
     {
       env: {
-        node: true
+        node: true,
       },
       files: [
-        '.eslintrc.{js,cjs}'
+        '.eslintrc.{js,cjs}',
       ],
       parserOptions: {
-        sourceType: 'script'
-      }
-    }
+        sourceType: 'script',
+      },
+    },
   ],
   parserOptions: {
     ecmaVersion: 'latest',
-    sourceType: 'module'
+    sourceType: 'module',
   },
   rules: {
-  }
-}
+    'max-len': ['error', {'code': 120}],
+  },
+};