<!DOCTYPE HTML>
<title>Fonts and margins of HTML headers</title>
<style type="text/css">

body > div { border: medium solid blue }
body > div > div { font-weight: bold }

</style>

<div><div style="font-size: 2.00em; margin: 0.67em 0">Level 1</div></div>
<div><div style="font-size: 1.50em; margin: 0.83em 0">Level 2</div></div>
<div><div style="font-size: 1.17em; margin: 1.00em 0">Level 3</div></div>
<div><div style="font-size: 1.00em; margin: 1.33em 0">Level 4</div></div>
<div><div style="font-size: 0.83em; margin: 1.67em 0">Level 5</div></div>
<div><div style="font-size: 0.67em; margin: 2.33em 0">Level 6</div></div>