<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
p.p1 {
margin-bottom: 5em;
}
p.p2 {
margin-bottom: 20%;
}
p.p3 {
margin-bottom: 20px;
}
</style>
</head>
<body>
<h2>Margin-bottom property example</h2>
<p>A paragraph with no margins specified.</p>
<p class="p1">Bottom margin is set to 5em.</p>
<p class="p2">Bottom margin is set to 20%.</p>
<p class="p3">Bottom margin is set to 20px.</p>
<p>A paragraph with no margins specified.</p>
</body>
</html>