1 2 3 4 5 6 7 8 9 10 11 12
<h1>Heading 1</h1> <h2>Heading 1.1</h2> <h3>Heading 1.1.1</h3> <h2>Heading 1.2</h2> <h3>Heading 1.2.1</h3> <h1>Heading 2</h1>