Boxception

<div class="a">
  <div class="b">
    <div class="c"></div>
  </div>
</div>

<style>
  body {
    background: #f3ac3c;
    display: grid;
    place-content: center;
  }
  .a {
    width: 200px;
    height: 200px;
    background: #1a4341;
    position: relative;

    display: grid;
    align-items: end;
  }

  .b {
    height: 100px;
    width: 100px;
    background: #998235;

    display: grid;
    place-content: end;
  }

  .c {
    height: 50px;
    width: 50px;
    background: #f3ac3c;
  }
</style>