adjusted GridBagLayout for buttons after winning

src/main/java/Gui/GameGui.java

@@ -78,6 +78,11 @@ GridBagConstraints gbc;
 		GameGui.ButtonPanel.setVisible(false);
 		
 		GridBagConstraints gbc = new GridBagConstraints();
+		gbc.gridwidth = GridBagConstraints.REMAINDER;
+        gbc.fill = GridBagConstraints.HORIZONTAL;
+        gbc.ipadx = 200;
+        gbc.ipady = 100;
+        gbc.insets = new Insets(20, 0, 0, 0);
 		
 		RestartBtn1 = new JButton("Nochmal Spielen");
 		ClosingBtn = new JButton("Schliessen");