It involves code editing, which is hard to do on a small screen.
Now when I remove that and add your "max-width: 100%" I don't see much of a problem. Sure, some content gets slightly misaligned on narrow screens but it looks pretty OK overall.
I just pushed the change now, should be visible within 5 minutes.
Being horribly old and needing glasses to see anything small but never having any glasses around, I find that my phone is pretty much useless for work. I guess I'm an outlier here. I'll just see what I can do to improve the mobile UX!