As you already figured out, you would first need to set the context width to
wide (100%), which allows you to build your custom "grid" layout without having it limited by the context width (which in itself is based on a "grid" when not set to wide). From there on, you can use X3's grid, which is based on the
Foundation framework:
https://get.foundation/sites/docs-v5/co ... /grid.html
Basically the grid allows you to control widths, use columns and decide how columns stack on smaller screens. Needless to say, this requires some patience to work with, as it's basically "web designer" stuff. I created the
www.photo.gallery home page layout with a custom grid, and it did take a while. But the grid is definitely your best friend if you want to create and manage a custom layout!