Luis, there wasn't enough time for my CSS presentation in the meetup. I will post a link to it on the boards instead, and possibly make a video on my own at some point, but for your specific question here's that rough outline I mentioned above:
Basically, the page consists of these elements with their respective style classes:
- $:/core/ui/PageTemplate/topleftbar
tc-topbar tc-topbar-left - $:/core/ui/PageTemplate/toprightbar
tc-topbar tc-topbar-right - $:/core/ui/PageTemplate/sidebar
tc-sidebar-scrollable - $:/core/ui/PageTemplate/story
tc-story-river
So you just reposition these by modifying their css classes.
Here is a demo example, in the presentation.
<:-)