#back{
  position: absolute;
  top: 150px;
  left: 370px;
}
#forward{
  position: absolute;
  top: 150px;
  left: 1450px;
}

#smartphone{
  position: absolute;
  width: 450px;
  height: 800px;
  left: 445px;
  top: 150px;
  z-index: -1;
}

#aufgabe{
  position: absolute;
  width: 325px;
  height: 700px;
  left: 965px;
  top: 150px;
  border-radius: 20px;

  background: #ffffff;

  font-family: Lato, sans-serif;
  padding: 30px;
  font-style: normal;
  font-weight: normal;
  font-size: 18px;
  color: #000000;
  z-index: -1;
}
#spickzettel{
  position: absolute;
  width:200px;
  height:250px;
  left: 1400px;
  top: 260px;
}