It would also be handy to have some visual guides for the indentation levels of nested comments as on Reddit. I've hacked my own indentation marks using a CSS injection for now, but this is clearly still not optimal:
I've also increased the size of the voting arrow because it's just uncomfortably small. By Fitt's law [0], smaller buttons require more time and effort to click!
Proper nesting layout will only work if they use proper nesting. Given the limitations - great job! I only use the first two lines as the png does not load.
[0] https://en.wikipedia.org/wiki/Fitts%27s_law