Unable to resolve C2084 error: 'Function already has a body' - C++

I am a beginner trying to practice the concept of Inheritance and tried building a piece of code but I seem to get this error. Maybe adding the virtual function is messing up my code? Here are my header and source files below:

1. Employee.h

    #pragma once
    #include<string>
   
    class Employee {
   
    public:
    std::string name{};
    int salary{};
   
    Employee(std::string name, int salary);
   
    virtual void displayDetails() {}
   
    };
   

2. Manager.h:

    #pragma once
   
    #include<string>
    #include "Employee.h"
   
    class Manager : public Employee {
   
    private:
    std::string department{};
   
    public:
    Manager(std::string name, int salary, std::string department);
    void displayDetails() override {}
   
    };
   

3. Employee.cpp

   #include<iostream>
   #include "Employee.h"
   #include<string>
   
   Employee::Employee(std::string name, int salary) : name(name), salary(salary) {}
   
   void Employee::displayDetails() {
        std::cout << "Name: " << name << std::endl;
        std::cout << "Salary: " << salary << std::endl;
    }
   

4. Manager.cpp:

   #include<iostream>
   #include<string>
   #include "Manager.h"
   
   
   Manager::Manager(std::string name, int salary, std::string department) : 
   Employee(name, salary), department(department) {};
   void Manager::displayDetails(){
        std::cout << "Name: " << name << std::endl;
        std::cout << "Salary: " << salary << std::endl;
        std::cout << "Department: " << department << std::endl;
    }
   

5. Main.cpp:

   #include "Employee.h"
   #include "Manager.h"
   #include<string>
   
   
   int main()
   {
    Employee e1("Robert", 5000);
    Employee e2("Sam", 8000);
   
    e1.displayDetails();
    e2.displayDetails();
   
    Manager m("Ben", 15000, "Marketing");
    m.displayDetails();
   
   
    return 0;
   }
   

This line in Employee.h:
virtual void displayDetails() {}

Implements displayDetails. The "body" of a function is what's in the brackets that follows its signature.

Therefore, when you attempt to "define" it in the .cpp, the compiler thinks you're trying to redefine the body because you already gave one in the header.

The correct syntax for what you're trying to do is

 virtual void displayDetails();
//                            ^~~~~~~~~~~~                    

Which is a function declaration (no body, i.e. no definition).

And of course, the answer is the same for Manager.h/Manager.cpp.