To elaborate it further, the problem common to every browser I tried (the only one missing is Safari) is that comments are nested and if I zoom the page to be actually able to read the text, I have to pain points now:
1) I have to keep scrolling right and left to keep them in view as I scroll vertically to follow the threads.
2) Even if 1 were not bad enough, the comments are too wide now to fit into the screen (remember that I zoomed in) and I have to horizontally scroll at each line. The only browser not to suffer from that is Opera which reflows text after a zoom (if you enable that option). I'm left with problem 1 but it's the least painful.
I suspect that a div layout would fare better, still there are tons of blogs with div layouts that end up with 10px wide comments at deep nesting levels. Maybe some media queries to remove nesting for devices not wide enough and adapt the page width after a zoom? I don't even know if the latter is possible.
Edit: I checked on the desktop and it seems that you already reduce nesting when the screen width is reduced, to the point of removing it at all. I wonder why my tablet and my browser are not affected and keep displaying the indentation to the left. Any browser, any user agent (desktop or mobile). They're 1600x2560px and 480x800px.
They said "It's a bad bug and we're going to fix it". So I'm waiting.
The indentation for one. Notice that the second comment is an answer to the first, but is on the same level of indentation. Following discussions like that is highly annoying.
Weird: While grabbing the phone to answer your question I noticed that "threads", i.e. the view of my comments, works fine. Just the comments below submission links are broken.
Compare to Chrome: http://m.imgur.com/Wpusprq
Note that I do use uBlock in Firefox. Now that I think about it, that might be relevant as well. But then again, why would that break the submission view and not the "threads" link?
(1) Lines are not terminated at the screen boundary on the tablet if I zoom in. They keep going off screen to the right. Same on the stock browser on the phone and with Opera if I turn off text reflow.
Dang - have you seen HN in Firefox on Android recently? Is there something we can do to improve this? Given that HN receives a moderate amount of (visible) changes recently, is there a way to make the site work in that situation/setup?