To have to play with my browser to reasonably read a HTML file annoys me, and I doubt I'm the only one.
Most people who have used an HTML browser for a while, HAVE fiddled with their browser, for example by setting their preferred text size. When the author of a PG HTML in turn fiddles with these factors, those fiddles override the fiddles already fiddled with by the reader. Now, only about 30% of the HTML written for PG is read on HTML browsers, whereas another 30% of the HTML written for PG is translated into EPUB format and read on EPUB devices -- which typically have a much smaller screen size than HTML browsers. And another 30% of the HTML written for PG is translated into MOBI file format and read on MOBI devices [aka: Kindle] To generate these EPUB and MOBI formats requires the translator programs to try to understand the fiddles fiddled with by the HTML fiddler in order to unfiddle them in order to refiddle them into the expectation of the EPUB and/or MOBI device and their limitations, and their preferences -- which typically is that the end reader of the document is allowed to fiddle with these issues NOT the author of the PG HTML. In turn then the creator of a MOBI or EPUB hardware device has to try to change their device designs to understand these fiddling and unfiddlings to refiddle in their hardware designs in order to meet the reasonable expectations of their customers to actually be able to read an ebook. Thereby leading to yet-another round of an escalating war of fiddling, unfiddling, and re-fiddling. Suggestion: It is NOT the job of a person creating HTML for PG to do the fiddling in order to make some particular hypothetical PG user's life supposedly easier. The user community of PG HTML is extremely wide and diverse, and when you think you are helping one particular class of PG user, you are probably unwittingly hurting some other large class of PG HTML users that you are unaware of. If you don't believe this, acquire real EPUB and MOBI devices, (such as a Nook and a Sony eReader and a Kindle and an Android Tab) and the various cellphones and take a look at the kinds of messes these various kinds of HTML fiddlings cause.