Portal

<div></div>
<style>
  body {
    display: grid;
    place-content: center;
    background: #f5d6b4;
  }
  div {
    width: 150px;
    height: 150px;
    background: #d86f45;
  }

  div::after {
    content: '';
    position: absolute;
    top: 125px;
    left: 75px;
    height: 50px;
    width: 50px;
    background: #d86f45;
    box-shadow:
      200px 0 #d86f45,
      100px 100px #d86f45,
      100px -100px #d86f45;
  }
</style>