Basic example

  <div class="parent">
    <div class="child"></div>
  </div>

  .parent {
    position: relative;
    height: 300px;
    width: 300px;
    background-color: lightblue;
  }

  .child {
    position: absolute;
    top: 100px;
    left: 100px;
    height: 100px;

    width: 100px;
    background-color: yellow;
  }

↓ ↓ ↓

final result: