                     row.add(rule: RuleRequired())
                     row.validationOptions = .validatesOnChange
                 }
+                .cellUpdate { cell, row in
+                    cell.contentView.layer.borderWidth = !row.isValid ? 2 : 0
+                    cell.contentView.layer.borderColor = !row.isValid ? UIColor.red.cgColor : UIColor.clear.cgColor
+                }
     }
     
     fileprivate func createBindings() {

                    row.add(rule: RuleEmail())
                    row.validationOptions = .validatesOnChange
                }
            +++ Section("Password")
                <<< PasswordRow() { row in
                    row.placeholder = "Enter password"

                    row.add(rule: RuleRequired())
                    row.validationOptions = .validatesOnChange
                }
                .cellUpdate(visualizeValidationError)
            +++ Section("E-Mail")
                <<< TextRow() { row in
                    row.placeholder = "Enter e-mail address"
