this page and the reduced file in attachment should print in landscape format, in fact they print in portrait
Created attachment 10597 [details] print
Your reduction is incorrect -- it has CSS rules inside a <script> tag: <style type="text/css"> </style> <script type="text/ecmascript" ><!-- @page {size: landscape} //--></script> A glance at the code shows that support for the "size" property isn't implemented, which is why your example fails to work as intended.
Created attachment 11855 [details] CSS test for printing landscape
updated patch in response to #2 cheers
Re-filed as bug 63575.