The up and down vote buttons next to each comment are very close together. It can be really tricky to hit the right one with your finger on a phone touch screen. There are numerous times when I just have to hope that the right one was selected. Can they be spaced farther apart?
I don't browse HN on my phone anymore, but I used to zoom in on the arrows every time I wanted to click them. You're right, it's quite a difficult target.
There are 3rd party iOS apps and I assume Android apps. I've used Octal which is free for browsing, but to log in requires a one-time payment.