Damon, I initially thought the iframe height was set in the CSS, but it appears to display as interpreted by the browser.
My initial view at 800 pix high was with Firefox 45.0.1. (I've attached the Firefox inspector plugin screen view.)
Viewing with IE10 I see the same 800 pix high, and with Chrome 49, the iframe is approx. 208 pix high, which isn't a problem.
I can't figure out what's causing this, myself.
~ Deborah