Wow, that's sorted it. Fantastic! After over three hours of faffing, chat response, and reading Squarespace help articles. Is it alright if I have a little cry? Or at least rest my head on the desk for a minute? 😄
Thank you so much Ziggy!!!
PS A slightly cheeky additional question for anyone following this (and tbh I don't really care anymore, I'm just glad it's done), but it seems to jump to the centre of the section the code block is in, rather than the section heading, which could be confusing. I'm guessing this is the only option.