Problem with the MM CSS layout tutorial

I am trying to learn CSS from the brilliant tutorials on Macromedia.com
The latest one I have tried is the basic layout tutorial, but I'm
having problems with it!
I'm sure the CSS is OK - I have compared mine with the exemplar (and in
the process learned how to detach a tabbed sheet!). However the MM
screenshot shows a white space below the nav bar; mine is above.
I can't find a finished file to compare it with so I am seeking help
here! Could someone check the code (so far) and tell me where I have
gone wrong ... but please be nice - I am a newbie to this game!

The site?
homepage.mac.com/zoolok/CSS_Layout/basiclayout1.html
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Be Seeing You
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Mark