I need to limit mouse follow in Unity2d

Question

i'm developing a little 2d sidescroller game, and i was wondering how could i stop my character from looking straight up in the air and directly onto the ground, so basically having a field of view of 45 degrees on both sides. Any advice?

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerMovement_script : MonoBehaviour
{
    private Rigidbody2D body;
    [SerializeField] private float speed;
    private Camera theCam;

    private void Awake()
    {
        body = GetComponent<Rigidbody2D>();
    }

    private void Start() 
    {
        theCam = Camera.main;
    }

    private void Update()
    {
        body.velocity = new Vector2(Input.GetAxis("Horizontal") * speed, body.velocity.y);

        if (Input.GetKey(KeyCode.Space))
        {
            body.velocity = new Vector2(body.velocity.x, speed);
        }

        Vector3 mouse = Input.mousePosition;

        Vector3 screenPoint = Camera.main.WorldToScreenPoint(transform.localPosition);

        Vector2 offset = new Vector2(mouse.x - screenPoint.x, mouse.y - screenPoint.y);

        float angle = Mathf.Atan2(offset.y, offset.x) * Mathf.Rad2Deg;
        transform.rotation = Quaternion.Euler(0f, 0f, angle);
    }
}

so this is the script for the player movement,thanks in advance.