Are you concerned about search engine optimization? If you make excellent use of CSS but your HTML lacks good structure, consider this quote from a 21 March 2007 PC Magazine article, “Remember that search engines read the HTML source code, so optimize your code so that it’s easy for bots to find keywords in the text.”
If you add structural elements, such as headings and paragraphs, search engine bots as well as people who use screen readers will be able to make better sense of the structure of your page. Understanding the structure means understanding the relationships between elements. For a search engine, this will highlight the important terms on your page. For a person using a screen reader, it will allow them to quickly navigate through the content of the page.