Add margin around page container so that the recognized text of one page doesn't run into that of the next page. 1.2em seems like a reasonable amount for readability. Could maybe go slightly higher.
I also added some margin on the bottom of the recognized text so it's not too close to the image of the page.
I think this should play nice with horizontal pages, but am unable to test because horizontal pages aren't working quite yet.
Also changed the default setting to 800px, which is a nice medium size to be legible but not too big. Max setting now goes to 1900 px (slightly larger than the 1872 px long edge of a Nomad page).
