This image is made of two screenshots : on the right hand side, a screenshot of resized to a 240px width. On the left hand side, a screenshot of exactly the same page with a zoom factor applied so the whole content fits into a 240px vertical gutter (think sizeToContent()). Many issues here :
  • the font-size issue I already reported
  • much more important, the radio buttons and checkboxes are not resized, completely horking some sections of the page
  • on the left hand side of the image, in the middle, you have this block of two columns od headers that is zoomed out into a block of only one column of headers and a white space at the right of the column.
  • the original resized screenshot is 240x949px. The screenshot of the zoomed out view is 240x1076px.

Again, as a a result, the position (think offsetLeft and offsetTop) of a given element changes between two values of zoom. To give a concrete example, this is a severe blocker for the mobile world to implement something like the thumbnail view/zoom view of the iPhone where the thumbnail would be a LIVE zoomed out page (with video playing and dynamic effects running) and not only a screenshot.

Update: filed under bug 400364.