In the Dawn theme on the product page, the container of the thumbnail image has a massive amount of padding-top set in the style attribute. It ends up being about 100% of the image height. It’s doing some weird calculation and I’m sure it’s probably done for a reason, but I can’t work out why it’s there. The following div wraps the image..
Also, all of the images I have for the products are tall and narrow. With Dawn having the width set at 100%, it makes them huge. Like, absolutely massively huge. I’d rather not go ripping out half of the code to make this work.