SOURCE

<div class="outer-wrapper">
  <div class="item-1">
    item-1
  </div>
  <div class="item-2">
    item-2
  </div>
</div>

.outer-wrapper {
  position: relative;
  /* z-index:1; */
  width: 200px;
  height: 200px;
  background: pink;
}

.item-1 {
  position: absolute;
  width: 280px;
  height: 50px;
  background: #2cef52;
  z-index: 0;
}

.item-2 {
  position: absolute;
  width: 250px;
  height: 50px;
  background: #2cd8ef;
  z-index: -1;
  left: 20px;
  top: 20px;
}