diff --git a/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/MainWindowController.java b/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/MainWindowController.java
index fd1a0d7..1468c22 100644
--- a/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/MainWindowController.java
+++ b/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/MainWindowController.java
@@ -118,6 +118,11 @@ public class MainWindowController {
             @Override
             public void update() {
                 results.setText(valueHandler.getResultBound());
+                if(valueHandler.areValuesOk()){
+                    results.setBorder(new Border(new BorderStroke(Color.GREEN, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, new BorderWidths(1))));
+                }else {
+                    results.setBorder(new Border(new BorderStroke(Color.RED, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, new BorderWidths(1))));
+                }
             }
         });
     }
diff --git a/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/ResultWindowController.java b/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/ResultWindowController.java
index bce37fd..c92142f 100644
--- a/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/ResultWindowController.java
+++ b/code/FXML-Calculator/src/main/java/ch/zhaw/prog2/fxmlcalculator/ResultWindowController.java
@@ -2,6 +2,8 @@ package ch.zhaw.prog2.fxmlcalculator;
 
 import javafx.fxml.FXML;
 import javafx.scene.control.TextArea;
+import javafx.scene.layout.*;
+import javafx.scene.paint.Color;
 import javafx.stage.Stage;
 
 /**
@@ -30,6 +32,11 @@ public class ResultWindowController {
             @Override
             public void update() {
                 results.setText(valueHandler.getResultBound());
+                if(valueHandler.areValuesOk()){
+                    results.setBorder(new Border(new BorderStroke(Color.GREEN, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, new BorderWidths(1))));
+                }else {
+                    results.setBorder(new Border(new BorderStroke(Color.RED, BorderStrokeStyle.SOLID, CornerRadii.EMPTY, new BorderWidths(1))));
+                }
             }
         });
     }