I think the problem is that there is not enough information on the event details page to fill the screen the way you have it designed. Try resizing your browser making it shorter to see the difference.
If you look at the main, outer table in the default template file, it specifies a height of 100% (not standard HTML code BTW). So when viewed in some browsers, the table will be stretched to fill the window vertically taking page elements along for a side (page position wise).
If you move your header code outside of the main page table, at least it should remain at the top of the page (hopefully). I don't know how the calendar elements will align though.
JFYI
Dan O.
[This message has been edited by DanO (edited August 27, 2004).]