DotNetNuke uses "Solparts Menu" as default navigation module. Unfortunately it generates a lot of "bad" tables.
Please have a look at the tutorial if you'd like to use the default navigation provider.
We recommend to use 3rd-party module, for example Snapsis.
Advantages of CSS NavMenu by Snapsis:
- semantic code (navigation list)
- a lot of templates (Flyout, Dropdown, Tabs...)
- maximum control through a template system
- optimized for search engines