I found Aardvark through del.icio.us. The product is a free Firefox plugin that allows you to check elements of a webpage and how it is constructed. It is particularly useful for non-geeks like me who want to customize templates of blog content management systems like WordPress or Serendipity.
Aardvark allows you to check parts of a site and see which HTML or CSS element controls its presentation. If you place your mouse pointer over a part of a page, the block will be highlighted an a text below the block will indicate which element it is.
With the tool, you’d know which part of your style sheet to edit if you want to change a part of your CMS-backed blog.