The first headline of a HTML document has to be of level 1.
The first headline will be transformed into a <h1>.
The body gets a <h1> as first child.
Enter the text of the new headline.
A <h1> element will be inserted before the first headline.
Enter the text of the new headline.
Delete the first headline (<>).
A headline on level 2 is missing: A <h3> should not follow on a .
Delete the headline <h3>.
Replace the <h1> by a <h2>.
Replace the <h3> by a <h2>.
Add a <h2> before the <h3>.
Enter the text of the new headline.
Add a <h2> after the <h1>.
Enter the text of the new headline.
The headlines on level 2 and 3 are missing: A <h4> should not follow a <>.
The headline on level 3 is missing: A <h4> should not follow a <>.
Add a <h3> before the <h4>.
Enter the text of the <h3>.
Add a <h2> and a <h3> before the <h4>.
Enter the text of the <h2>.
Enter the text of the <h3>.
Replace the <h4> by a <h2>.
Replace the <h4> by a <h3>.
Delete the headline <h4>.