.calculadora{
  display:block;
  margin:0px;
  padding:20px;
  background-color:#2980b9;
  width:340px;
  height:500px;
  border-radius: 25px;
}
.calculadora td button{
  display:block;
  width:70px;
  height: 70px;
  font-size: 25px;
}
#creditos{
  display:block;
  padding-top:20px;
  color:#fff;
  text-align: center;
  width:300px;
}
#resultado{
  display:block;
  text-align: center;
  font-size: 40px;
  margin-bottom: 50px;
  width:300px;
  height: 100px;
  line-height: 100px;
  background-color:#fff;
  border-radius: 25px;
  overflow-y: scroll;
}