<!doctype html> <!-- Any copyright is dedicated to the Public Domain. http://creativecommons.org/publicdomain/zero/1.0/ --> <meta charset="utf-8"> <title>CSS Test Reference</title> <link rel="author" title="Emilio Cobos Álvarez" href="mailto:ecoal95@gmail.com"> <style> .container { background: gray; height: 80px; } .panel { background: lightblue; width: 150px; height: 80px; } .contents { height: 10px; width: 10px; background: purple; } </style> </head> <div class="container"> <div class="panel"> <div class="contents"></div> </div> </div>