Products only display in one column after Hikashop Business upgrade

-- url of the page with the problem -- : www.dsgbutiken.com/index.php/tillbehor-bil-lastbil/olja-filter
-- HikaShop version -- : 3.1.1
-- Joomla version -- : 3.7.2
-- PHP version -- : 7.0.15
-- Browser(s) name and version -- : Anyone

Hi,
After upgrading to HS Business 3.1.1 my products display only in one column.
No changes made, I have it set for 4 column display but that doesn't work anymore.
Please someone advice how to get the 4 column layout back.

Thanks,
Micke

This is obviously a common problem. Thanks for the quick reply. The other threads only vaguely inform my particular issue. I wondered if you could possibly take a glance here? roguesailing.org:8080/index.php/all-products
You will probably know almost instantly what's causing the problem. I can fix any code or script if pointed in the right direction. Your help is always appreciated.
-Jim Gribble

Jerome, I hunted it down in the old.css file. Thanks for the clue.
-Jim Gribble

frontend_old.css, line 46, to be exact, for anybody else looking for it.
-Jim Gribble

This solved a big problem, but not entirely. In div layout, rows display unevenly. Some show two products and a gap where the third should be. It is not an issue with the individual products because I experimented with unpublishing the ones in the vicinity of the "gaps." This is a new one, and I wasn't even sure what to type into the search window. I am attaching screen shot by way of explanation.
-Jim Gribble

When I toggle to use default.css, the issue goes away, but the products don't look as nice. Still fiddling.

Thanks I did kind of figure this out on my own. Why though would I even want to use the old css instead of the default? When I switched to the default everything worked better. I certainly am seeing the virtue of the custom.css system for fine-tuning the view.
-Jim Gribble

Thanks for the tip. I generally do as your suggesting and keep a log of all edits. This is a good nuance for everybody to know, especially those of us who do highly designed sites in which all the elements have to have a visual harmony.
-Jim G.