Row with variable width columns

Hello: I have a real life need.

A row has the option to set the number of columns and their width.

In order to use the background image (parallax), the need is to use one row with variable columns (with different number of columns and width of them) inside a single row.

This need, in order for the background image to cover the three different containers in this image.

This is the page in the front end. The section that holds the “Call to action widget” is the one with the parallax background image. The need is to extend the background image to the sections below here, as you will see when you scroll down.

Any setup to accomplish this?

Thanks

The page I need help with: [log in to see the link]