I added the style-option width="100%" to the second (inner) table (for the main page) to rectify a problem described here http://forum.openstreetmap.org/viewtopic.php?pid=132049#p132049 (unfortunately in German).
Without this style-option, one observes problems with right-aligned floating objects in the main page, such as they are used by the Place template. Without this style-option the box for the page content (the inner table) is as wide as the widest paragraph. This means, that right-aligned floating boxes are not placed at the right side of the page but are aligned with the right end of the widest paragraph.
Regarding the Place template, the green box is a right-aligned floating box. Without the added style-option this box may in the extreme be placed almost at the left side of the page with the map (if displayed) being positioned below. In order have the map and the green box for the page details to be displayed beside each other and the green box to always be positioned at the right side of the page, one has to make the inner table fill all available space -- with is what this style-option does.
P.S. Well, this is at least my understanding of how it works. Anyway, my experiments are compatible with my explanation...