I was aware of a few more solutions to this, which were not applicable here because of their inflexible nature. But finally I found *two* solutions which will work:
The easiest seems to be the "overflow: hidden;" solution. Although that works fine on the new default template, it doesn't on the old one, because of the way the lists are built. So, we could still implement that solution but would need to re-style all of the lists. That would need proper testing, because lists are used everywhere (not just in the main page content).
The other solution is "position: relative; left: 1.5em;". That would require a lot of changes and would probably break a lot of plugins. So, I wouldn't recommend doing that.
I just fixed it on the new default template. Do you think it's worth changing that on the old default template as well?