Z-index trouble

I was trying to put the box I made behind the survey form so that you can see the survey questions. However, the z-index doesn’t seem to work.

box{
  width: 510px;
  height: 400px;
  text-align: center;
  position: absolute;
  background-color: pink;
  top: 120px;
  left: 380px;
  z-index: 1;
}
#survey-form{
  font-family: helvetica;
  text-align: center;
  padding: 20px;
  z-index: 2;
}```

The z-index starts at 0. Maybe that’s the problem?