title: Golang gorilla mux not found handler doesn't work correct
body: <p>I'm writing a web server and I've got Not Found Handler function.
  All the Handle functions like login, registration, view page are working correctly.
  I also have such line: <code>router.NotFoundHandler = http.HandlerFunc(Handlers.NotFoundHandler)</code>
  Handlers is my package including next code:</p>
  
  <pre><code>func NotFoundHandler(w http.ResponseWriter, r *http.Request) {
      //title has to be 404.html
      title := config.Page404
      title = config.WebAppex + title
  
      fmt.Println("title: " + title)
  
      /*HERE IS QUESTION LINE*/
      r = http.NewRequest("GET", config.Page404, nil)
  
      fmt.Println(r.URL.Path)
  
      logger.Info("Sending... ", title)
  
      //load page
      p, err := loadPage(title)
      if err != nil {
          logger.Error("ERROR : ", err.Error())
          p, _ := loadPage(config.Page404)
          fmt.Fprintf(w, "%s", p.body) //wired way to send HTML page
          return                       //just return because of printing dry p.body
      }
  
      //serve it
      http.ServeFile(w, r, p.dir)
      logger.Info(p.dir, " has been sent")
  }
  </code></pre>
  
  <p>So the problem is: If I try going to localhost:8080/nothing, then I get my nice Page404
  But if I go to localhost:8080/nothing/nothing or localhost:8080/nothing/nothing/nothing and etc, I get dry 404.html without any CSS. So I thought that problem is request, so I create new with the way of "/404.html" (it's config.Page404), but nothing changed. I read about gorilla mux Subrouter, bit It may help to exclude only localhost:8080/nothing, but I need all the cases. So is there any ways to exclude all the not existing pages?</p>
  
  <p>UPD: My loadPage function:</p>
  
  <pre><code>func loadPage(title string) (*page, error) {
      logger.Info("Trying to load", title)
      //writing from title to body
      body, err := ioutil.ReadFile(title)
      if err != nil {
          return nil, err
      }
  
      return &amp;page{dir: config.HOMEDIR + title, body: body}, nil
  }
  
  type page struct {
      dir  string
      body []byte
  }
  </code></pre>
  
  <p>Thank you!</p>