保存summernote内容时CSS属性消失了

I am using summernote as my WYSIWYG editor. So I have submitted its contents through ajax using formdata. I've done the following:

 formdata.append('content', $('.summernote').code());

So my PHP accepted it and save into my database. However, all css properties were gone upon saving like font style and font sizes etc. I am using CodeIgniter in my php and this is my code in saving:

     public function save_spot_report($data){
            $to_return = true;

            $this->db->trans_begin();
            $this->save_spot_report_details($data);
            if($this->db->trans_status() === FALSE){
                $this->db->trans_rollback();
                $array['error_message'] = $this->db->_error_message();
                $array['error_number'] = $this->db->_error_number();
                $to_return = $array;     
            }else{  
                $this->db->trans_commit();

            }

            return $to_return;
        }

        public function save_spot_report_details($data){
            $this->load->library('DateTimeHelper');
            $data['created_by'] = $this->session->userdata('username');
            $data['date'] = $this->datetimehelper->get_current_date();

            $config['table'] = 'spot_report_tbl';
            $config['data'] = $data;

            $this->special_save($config);

        }
public function special_save($config){

            if(!isset($config['type'])){
                $config['type'] = "INSERT";
            }
            if(strtolower($config['type']) === "insert"){
                $this->db->insert($config['table'],$config['data']);
            }else{
                $this->db->where($config['conditions']);
                if(!isset($config['use_set'])){
                    $this->db->update($config['table'], $config['data']);
                }else{
                    $params = $config['set_params'];
                    $this->db->set($params['param_1'], $params['param_2'], $params['param_3']);
                    $this->db->update($config['table']);
                }

            }
            return $this->check();
        }

Your responses will be greatly appreciated! Thanks!