So the correct way of HTML-Mobi conversion is on Win.gif picture, isn't it? All paragraphs except of headings should have indents.
Howere I like this workaround. Indents are mostly used for paragraphs separation only and they are not needed to be shown under headings or pictures. I have no idea how I would do it in Calibre with paired <P></P> tags, so I'm very glad for this behaviour :-)