I am redesigning a site in Site Designer V3 (going from mobile up to desktop). At the narrow breakpoint (think smartphone width), I want everything in one column. At a laptop/desktop computer-width breakpoint, I want there to be 3 columns with a gap in between each. Basically, one center column for the main content & a left and right sidebar for a calendar listing & "about us" section. I have figured out how to make a column narrower than the full width of the viewport by setting the container width to 50%, but can't figure out how to have 3 columns side-by-side. If I try to add a container div to the parent container div for that content (to create a second column), it just goes between the heading & paragraph elements. It won't sit beside the main column (that contains my heading & paragraph text). If I set the second "column" container to Flex, I just get a tiny sliver of a column that is still basically between the heading & paragraph text elements. Is there a way to do a multi-column layout that I just can't figure out, or am I banging my head against a brick wall with no possible solution? I'm attaching a screenshot of part of the current site to show the sort of layout I want to achieve. Thanks in advance for any advice.

Like this?

Yes--thank you! Instead of pictures, I want text blocks, but the design is exactly what I want. Is there a step-by-step or something as to how I could achieve that?

I just banged in something in the different containers. I've done nothing as to styling, as I thought you would rip out whatever I put in and fill the framework with your own contents.

The easy way of achieving this layout is to select the 'parent' container from the file I sent you, and save it as a component. Then you can open your own project and add that component where you need it.

If you want to do it yourself, you have to add a container (the parent) and make it display flex. On wrap you set it to 'wrap'.
Then you add three more containers inside the parent (the children). Make sure they don't end up inside each other, but below each other. I called the middle one 'child-wide'. Those containers will look as narrow stripes before they have any contents.
You may want to add some padding. I would give side padding to all 4 containers in order to get some gap between them.
After you have added some contents, move the slider past the first breakpoint, and change the wrap to 'no-wrap', and I think it will look ok if you select 'space-between' at the Justify setting. Now the boxes will have the same width, so you need to give them all a %age width. I went for 25/50/25. Choose what fits your design.
So, that's all I did.

Thank you so much! I did have to do some tweaking, but was able to get it to work!!!