Symple shortcodes: how to create rows and columns?

Hi

I’m using wp-pytheas theme that has symple shortcode addon.

I’m trying to create multi column content which is fine for the columns part.
However, columns are broken when rendered for example only two columns fits the row and third one runs on second row.

How does it create row, columns and how widths are defined?
i tried googling but couldn’t find anything.
Source code is a option but the last one…