If you all think JavaScript frameworks spit out horrendous code, try editing an epub file in Calibra (it’s XHTML). As well as dealing with mountains of span tags, it took me hours to track down the cause of a bug where numbers in my ebook were formatted differently from the text…the reason, it turned out: one of the meta files had an Arabic language setting! I only discovered this when I looked closer at the settings on my kindle. All part of the fun of being a self-published author :)