User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:57.0) Gecko/20100101 Firefox/57.0 Build ID: 20170812100345 Steps to reproduce: I opened up a Keynote-generated HTML file in Firefox (see attached file for example, just open the "index.html" file inside) and began to play through the slideshow. Actual results: Many slides had text being cut off in titles and descriptions. Expected results: The text in the slides shouldn't of been cut off and should have display the text completely without cutting off the end of words. This presentation currently displays correctly in the latest versions of Chrome and Safari.
I believe Apple optimizes any exported HTML to Safari. The problem should rather be reported to Apple.
I have reported it to Apple already quite a few times over the past few years and they haven't changed anything, but then since it works in Chrome as well as Safari I thought it was just a Firefox rendering bug, hence why I've filed it here.
Because Chrome is built with the same rendering engine as Safari (now forked) it makes sense that it only works on Safari and Chrome.
After doing some more experimentation, it seems to have something to do with the way Firefox renders the font Century Gothic Bold. In comparing the thickness of the bold font-size of Century Gothic to the way it looks in Safari and Chrome, it seems like Firefox makes the font display extra thick, which then makes the font widen out too much which is why the text gets cut off. It seems to me that this stems from a font-rendering issue but only in the bold version of that font. To see this compare the additional files I've attached.