<!doctype html>
<title>CSS Test Reference</title>
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<style>
  body, html {
    margin: 0;
    padding: 0;
    background: green;
  }

  .purple-square {
    background: purple;
    width: 50px;
    height: 50px;
  }
</style>
<div class="purple-square"></div>
