Thanks Guys.

The pointers about fixed widths of columns have been incredibly helpful and have enabled me to fix some of our pages.

Others though just seem to refuse to scale properly.

For example on this page,

https://www.stoneleighlibrary.org.uk/classes-and-groups/

even if I delete the original content and just create a two-column table - with the table width set to 100% I get the left column displaying correctly on my phone but the right column is obscured. I have given up for now. It just seems a bit random.

Thanks for your help.