I intended to write how I did it, but I was caught up in other commitments, and I wanted to have a working example ready.
But here is what I did:
I wanted sidebars on either side of a main content area, so I inserted a row and gave all of it (make sure that 'row' is selected) the background colour I wanted to use for the side bars. After that I split it up in three columns and adjusted the span for each of them. Still all has the same bg colour. I inserted a subgrid into the main content area (I only needed one row/one column in that subgrid). Then the subgrid got a different bg colour. Now I added a couple of paragraph elements into the subgrid, and voilà: the side bars are expanding downwards as the main column is filled with text.
The bits of colour that peeks out below the subgrid can be removed by adjusting the margins.

I guess someone who has never coded a site may have a faster understanding of RLMP, as there isn't so much they have to 'unlearn'. Even if the margin, padding etc have been there for years, it's a new way of using them. And I had never heard about 'push', 'pull' nor 'hero element' before. Grids - yes, but if you are a die-hard coder, like me, you don't use grids. It is hardly possible to make everything fit into a grid anyway, and I have always maintained that if I have to change my design to fit into a grid, then I won't use a grid. I'm certain that I'm not the only one thinking that way.

You have been with the CC staff for as long as the RLMP has been around, Adam, and I'm sure you know the ins and outs of it. Well, some (many) of us have not fiddled with it that long, and therefore have to find out things. And that is the learning curve I was talking about. Of course, when you have found a solution to a problem, then it's that aha moment you are mentioning. I for once have had a couple of those already, but I still have a lot to learn. Oh, and the background issue and how I solved has been explained in my previous post.
I can see the programme has some great features. But for the time being, I would probably be able to complete a responsive design faster by coding it myself. That might change, though, you never know...

It will change. The more you use it the more you understand it is the same yet slightly different.

And when you do Inger, you will finally have the "Ahhhhh...." moment. That is all Adam is saying. Once you understand it, things make sense.

We can always live in hope...

We keep saying that every day.

If you CC guys can just bear/bare (never sure which one that is ) on us with RLM, regardless of whether you think the questions are simple. I agree 100% with Inger it is more suited to non-coders. There is nothing that I've ever come across more difficult than programming and I've done Maths to a pretty high standard and that to me is simple compared to programming languages, but when we say there's a learning curves there's a learning curve. There is a time when you get that Eureka moment and you think yeah that's clicked. I'm doing quite well with RLM now, I'm not a guru but it's coming.
All we ask is just for this time period with a new powerful program and the arm bands are still on, just answer the questions. In a few weeks when others come to the party and they are using RLM we can answer their questions

Why would we stop helping? Have we ever said "Sorry, we can no longer help you out. Figure it out yourself."

Adam gave a pretty detailed response to the question at hand. This topic is starting to stray from the original question...

Actually... when you say "Not being a little condescending" is sort of condescending.

What Adam said was that the markup is nothing really new. This code has been around for a long time. Sure the application itself may have a bit of a learning curve but adding your content to it should be relatively straight forward for those who already code websites. It is just HTML and CSS.