Wordpress Over-riding My Formatting

I've ported the Wordpress app from wordpress.org to my web site. I've changed the html and the css to conform to my existing开发者_运维知识库 design. I've placed the entry data in my 'main' div, which has a left margin of 19em to keep it to the right of my navigation div. This margin appears to be overridden somehow by the generated html within the 'main' div. I've patched some of the elements by adding the margin back to them, but would prefer a cleaner fix. I've looked at the page using Firebug, but I can't identify the appropriate entry. What is overriding my margin setting?

The problem page is here. Notice the Tags at the bottom. Another page that doesn't use WordPress code doesn't have this problem. It is here.

Thanks for any help

I want to keep my acceptance rate high so I don't appear ungrateful for all the great help on this site. The answer was that the css was defined as a class and the html was using 'id='. Sometimes it helps to make sure the computer is plugged in.