I have an ebook that I'm trying to make adjustments to. When I load it on my Nook Simple Touch, it has large margins, ignoring the settings on the Nook to have a minimal margin. When going through the HTML for the ebook, nothing jumps out at me as causing this large margin. After I make changes to the CSS, I need to package the files back up as an epub, copy the file to my Nook, and then see if I fixed it. That whole process is time consuming, especially since I'm testing one minor change to the CSS at a time.
Is there some software that will simulate the epub renderer of an ereader on a computer and let me inspect the DOM to see why it's maintaining large margins on an ereader?