body {
    background: gray;
  }
  #firstDiv {
    background: blue;
    width: 100px;
    height: 100px;
  }
  #secondDiv {
    background: yellow;
    width: 100px;
    height: 100px;
  }
  .absolutePositionExample {
    position: absolute;
    top: 20px;
    left: 20px;
  }
  .relativePositionExample {
    position: relative;
    top: 20px;
    left: 20px;
  }