If you’re running the Jetpack and have enabled the Custom CSS, you can add this to it. That worked for me.
.featured-wrapper {
float: left;
}
.content-wrap {
float: left;
}
Ordinarily, in the main style.css, these classes float right to force them to the right of any sidebar you have loaded on the left.
You have two main “content” areas, the “content-wrap” class is used for pages, posts, and on the main featured content page, for Recent Articles etc. However, the featured posts with the slider live inside the “featured-wrapper” class so you have to float that left as well.
Important note: if you add items back into the Primary Widget area, they’ll appear to the RIGHT now of your main content. So the “float” attribute acts as a “swap” or “flip-flop” for where the widget will appear.
That’s fine for my purposes, but if you want to actually completely remove the sidebar from the markup and have your content then act “full width”, that’s another question!