Sorry, perhaps I should have said that this solves the problem in the short term. Hopefully, One on the admins will pick up on it and check the forum settings and/or stylesheet 'overflow' properties.
I'm afraid that I don't have access to change those, although I can see that the class
.content has the overflow set to hidden. Changing this to
overflow: scroll would add a scroll bar; when I recreate it on my server, this changes it to this:
Ideally, it would be great if there's a setting in the forum software that adjusts the picture size, rather than add a scrollbar. I'm sure that someone will advise further in due course whether this is possible.
Phil