<!DOCTYPE html> <meta charset="utf-8"> <title>CSS Reference: A green box</title> <link rel="author" title="Xidorn Quan" href="https://www.upsuper.org"> <link rel="author" title="Mozilla" href="https://www.mozilla.org"> <p>Pass if there is NO red below:</p> <div id="ref" style="width: 100px; height: 100px; background: green"></div>