Displaying one div on top of another

Answer 1

Have the style for the parent div and the child divs' set as following. It worked for my case, hope it helps you as well..

in your JS:

document.getElementById('parentDiv').style.position = 'relative';
document.getElementById('backdrop').style.position = 'absolute';
document.getElementById('curtain').style.position = 'absolute';
document.getElementById('curtain').style.zIndex= '2';//this number has to be greater than the zIndex of 'backdrop' if you are setting any

or in your CSS as in this working example:::

#parentDiv{
  background: yellow;
  height: 500px;
  width: 500px;
  position: relative;
}
#backdrop{
  background: red;
  height: 300px;
  width: 300px;
  position: absolute;
}
#curtain{
  background: green;
  height: 100px;
  width: 100px;
  position: absolute;
  z-index: 2;
  margin: 100px 0px 150px 100px;
}

  THIS IS PARENT DIV
  
  

  THIS IS BACKDROP DIV
  
  

  THIS IS CURTAIN DIV