Ask yourself, what is a web developer? I think initial thoughts lead to believe that it is one who develops web pages for individuals and/or companies. Those initial thoughts are correct, but there is more to it. Developers also manage the all of the technical aspects that the common person is inept to do. A web developer also has the ability to reach into their creative side. Either on their own or with guidance from the client the developer is able to desing the overall layout and appearance of the web site. I think we all can agree that some web sites have layouts and user interface deficiencies that make them a hassle to use.
Examples of specialized web developers from Occupational Outlook Handbook: What They Do
This video shows the development of this website and validating the code through W3C CSS validator and W3C Markup Validation Service. It is important to routinely check your code as you build the website to address errors as they occur.