As I have a tendency to dive in with new software as my way of learning how to use it, when I first started with RSD I hadn't noticed/realised that when you use the slider thingummy at the top to set the width of the web page, that it could go to the full width of the screen because of the tool box on the right of the screen, which then ends up over the top of the area you may be editing/working on (not a clever setup, I'd like to have the ability to move that around so it doesn't obliterate areas I want to work on...), so as a result I didn't realise that in setting things up in the visible screen it would look different when it was on a wider screen. I think that makes sense to me now!
Apologies for you having to look up "sussed" - It didn't occur to me that anyone might not have come across it before!!
I think I am slowly getting to grips with RSD and certainly switched it off last night feeling like I'd made enough progress to know where I needed to get on when I get back to it again, either later today or tomorrow. However, for now, proper paid work calls so had better get back to that before I get stuck into more website stuff!!