3.6:H203005 Nest headings properly.

Improper design

In the Chinese version of this example, the titles of the three layers were not used according to the H1~H6 labels.

<H1>first layer title</H1>
<H3>third layer title</H3>
<H2>second layer title</H2>
          

Proper demonstration

The example provided the proper use of<H1><H2><H3>labels in the orderly form, such that H1 was followed by H2, and then H3.

<H1>first layer title</H1>
<H2>second layer title</H2>
<H3>third layer title</H3>