Offset loop for related posts

Hello.

I wanted to create an offset loop for my related posts which are wrapped by a scrollable container. I want the newest 4 related posts show up in the first div, the next 4 in the next container, this should go up to 12.

My original setup looked like this:

[code moderated - please follow the forum guidelines for posting code]

Then, I tried something like that, but I keep getting syntax errors such as "syntax error, unexpected T_ENDWHILE":

[dito]

I'm really going crazy here and have tried to close tags at all sorts of places, but it just doesn't work. I hope somebody here can help me figure out where I went wrong. Thanks a lot!