I had some HTML that I thought was perfect (converted from eReader, gone through and stripped of all code, saved with text editor etc) and they display fine on all my devices except a Libre I am testing. There are no line breaks in the mobipocket files on the Libre where there were on the Kindle. Someone told me I might not have used the right code. I have been finding that epub and a few other supported formats are showing up fine on the Libre using the same batch of files as my base for conversion, so short-term, the problem is solved. But I really don't want to be dealing with further issues every time I use a new device, so I am interested in getting my source files as clean as possible.
Even in the files which are now displaying better as epub, there is a problem with double line breaks not showing up. So I am wondering if the problem is mobi, or Calibre, or whomever not recognizing double line breaks. My document is plain text and what I had been doing was using Text Wrangler to replace the extraneous line breaks with double line breaks <br><br> If I do a find and replace and replace every <br><br> with </p><p> (to end the current paragraph and then start a new one) will that solve all my problems? If I have plain text with only these formatting marks, will I at last have clean HTML that will convert to anything?