title_body: How to simulate an epub ereader and inspect its DOM? 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?
upvoted_answer: For editing an EPub, I would look into sigil. It has the ability of WYSIWYG editing and comes recommended by other users on this forum. It's free and open-source.
  
  An alternative is Calibre. Editing EPubs is a bit more code-centric in contrast to sigil. It's also free and open-source.
  
  For some comparisons between the two programs, check out this blog.
  
  As far as an actual hardware emulator for specific eReader devices, I'm not aware of any.