if Length(Edt_Username.Text) = 0 then
  begin
    Edt_Username.Color := clRed;
    Edt_Username.Font.Color := clWhite;
  end
  else
  begin
    Edt_Username.Color := clWindow;
    Edt_Username.Font.Color := clWindowText;
  end;
  if Length(Edt_UserID.Text) = 0 then
  begin
    Edt_UserID.Color := clRed;
    Edt_UserID.Font.Color := clWhite;
  end
  else
  begin
    Edt_UserID.Color := clWindow;
    Edt_UserID.Font.Color := clWindowText;
  end;
  if Length(Edt_Abteilung.Text) = 0 then
  begin
    Edt_Abteilung.Color := clRed;
    Edt_Abteilung.Font.Color := clWhite;
  end
  else
  begin
    Edt_Abteilung.Color := clWindow;
    Edt_Abteilung.Font.Color := clWindowText;
  end;
  if Length(Edt_Room.Text) = 0 then
  begin
    Edt_Room.Color := clRed;
    Edt_Room.Font.Color := clWhite;
  end
  else
  begin
    Edt_Room.Color := clWindow;
    Edt_Room.Font.Color := clWindowText;
  end;
  if Length(CB_Mandant.Text) = 0 then
  begin
    CB_Mandant.Color := clRed;
    CB_Mandant.Font.Color := clWhite;
  end
  else
  begin
    CB_Mandant.Color := clWindow;
    CB_Mandant.Font.Color := clWindowText;
  end;