Ensure correct semantic use of header tags

[zackharley]

When using the <h#> tags (i.e. <h1>), ensure that you are using them semantically. These should be used for headings and subheadings. If you need to have bolder or larger text, use CSS to style the tags.

[zackharley]

Are all of the header tags necessary? Specifically this. Also, there is no <h4>. It goes from <h3> to <h5>. Is that intentional?