adjustments to me camera follow script

Hey, I have this camera script that tracks the player and the mouse. The camera follows the player and allows the mouse to be used to pan around slightly while keeping the player in view. I've refined it quite a bit through playing around with different variables but it isn't perfect. I was hoping someone who better understands code could take a look at it.

 using UnityEngine;
 using System.Collections;
 
 public class CameraFollow : MonoBehaviour
 {
     public Transform target;            // The player that the camera will be following.
     public float smoothing = 5f;        
     int floorMask;
     float camRayLength = 100f;
     Vector3 cameraToMouse;
     Vector3 offset;                     
 
     void Start()
     {
         floorMask = LayerMask.GetMask("Floor");
     }
 
     void FixedUpdate()
     {
 
         Ray camRay = Camera.main.ScreenPointToRay(Input.mousePosition); //point ray from camera to floor
         Vector3 camCenter = Camera.main.ScreenToWorldPoint(new Vector3(Screen.width / 2, Screen.height / 2, Camera.main.nearClipPlane));
         RaycastHit floorHit;
 
         if (Physics.Raycast(camRay, out floorHit, camRayLength, floorMask)) //if ray hits floor
         {
             cameraToMouse = floorHit.point - (new Vector3 (transform.position.x, transform.position.y, (transform.position.z +6))*2) + (target.position/2);  //assign hit point vector to variable
                        
         }
 
 
 
 
         // Create a postion the camera is aiming for based on the offset from the target.
         Vector3 targetCamPos = target.position + cameraToMouse;
         targetCamPos.y = 4f; //lock camera at current height
 
         // Smoothly interpolate between the camera's current position and it's target position.
         transform.position = Vector3.Lerp(transform.position, targetCamPos, smoothing * Time.deltaTime);       
     }
 }

The parts that need tweaking are the cameraToMouse variable and the targetCamPos. Right now the player can catch up to the edge of the screen which I don't want to happen. What should I change to make the camera keep up with the player?