Webpage drops from the top of the browser page

This webpage drops from the top of the browser page https://www.ottawapatentagency.com/affiliations.html 

All other webpages of the site are flush to (don't drop from) the top of the browser page, for example https://www.ottawapatentagency.com/forum.html 

All webpages of the site are coded in the exact same way:

• there is a container in the body of the html page
• inside the container is the sidebar1 (navigation on the left) and the content (on the right)

Why does the particular webpage (and only that one) drops from the top of the browser page?

Thanks!