<!doctype html>
<meta charset="utf-8">
<style>
  body {
    margin: 0;
  }
  .red {
    height: 100px;
    width: 100px;
    overflow: hidden;
    background-color: red;
  }
  .green {
    width: 100px;
    height: 100px;
    position: absolute;
    left: 0;
    background-color: green;
  }
</style>

<div class="red"><div class="green"></div></div>

