Document preview sets container size incorrectly when zooming

Looking at this [document](https://oae.oae-release0.oaeproject.org/content/oae/e1HlWQjJI)

At it's natural size (100% zoom) it's 1235 x 82 pixels and the height has no problem fitting in the container:

![screen shot 2013-12-04 at 2 44 31 pm](https://f.cloud.github.com/assets/1731910/1676646/04dfd384-5d1d-11e3-8aba-8bfb89a5d4fc.png)

When zoomed to 200%, however, the content appears to take up much more vertical space than is necessary. In the screenshot below the page is scrolled up to show the excess:

![screen shot 2013-12-04 at 2 45 11 pm](https://f.cloud.github.com/assets/1731910/1676671/5754ac8e-5d1d-11e3-98b6-6f8af430f93b.png)

There are actually a couple of problems (maybe related):

1. There shouldn't be the extra whitespace below the page.
2. And even if the whitespace is legitimate, the resulting content should still fit comfortably within the maximum 700px height of the container, so no scrolling should be required to see the whitespace.

The problem is much more severe at 500% zoom, but it's easier to see in the 200% screen shot above. (At 500% zoom all the shadows -- on all 4 sides -- are missing so it's a bit hard to tell exactly what's going on.)

Doesn't seem like a blocker issue.