Problem Solved

 For Examples:  ElevatedButton(               style :  ElevatedButton. styleFrom (                 primary :  Colors.deepOrange,  //This is ...

To initialize Firebase we should add this in the main.dart with the following example: void   main ()  async  {    /// Firebase Initialize  ...

You can install http-server from node package manager after your installed it then just run by npx http-server in the build/web directory