When I was in primary school, at around 10- or 11-years-old there was a popular website that gave you a homepage and had challenges for doing things like making the header a certain size or having images and so on, I remember thinking it was really cool

I think it was called Grid<something> or <Something>grid, I just had a look but couldn't find it

Think it was somehow linked to schools, this was in the UK around 2005