Hi.
I think you do not quite understand how it works. You need to use the only section by making it the desired layout and place all the content only in this section. What will deprive you of the opportunity to use background images of full width.
Instead of an accordion, it is worth using the standard menu module so that there are correct links on the site and bread crumbs work. And of course a little CSS will need it to stick.
In fact, a bad idea to use SPPB to build a catalog. It is better to use the standard blog or some online store component.