Originally Posted by Difflugia

Though I'm sure this is true to a degree (and more true for some publishers than others), I don't think it's primarily the fault of the publishers. When I use HTML/CSS the way I would for a browser, different ebook readers and software don't render the result correctly and consistently. If I want the ebook to look presentable with multiple devices and apps, I end up having to target the least common denominator and change things like <h1> to <p class='heading1'> just to make sure that results are consistent across multiple platforms. I actually have a set of search-and-replace macros so I don't have to write the source like that, but can wait until after I'm done to dumb it down.