Change margin on category display between tiles

-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.3.6
-- Browser(s) name and version -- : any

I want to change the margin between tiles in the category view.
In the Display details of each product category there´s a section "Parameters for DIV"
Changing the margin in this setting will change the top, left, right, bottom margin in parallel.
I only want to change margin left and right only. I´m using the type of item layout "Image and title".
I also do not find any options in the css.

Of course the CSS needs to be added using class or ID.
But I don´t find the related code in the php file. When looking at the HTML code via the browser I see the relevant code phrase, but I can not find something similar in the php. As mentioned I´m using the type of item layout "Image and title".

Sorry nicolas, that does not help.

I try to describe the issue again.
In the source code I identify a line

#hikashop_category_information_menu_129 div.hikashop_container {
margin:5px 5px;
}

The margin entered in the backend (section "Parameters for div") will be written into this line (see attachment in post #187871).
If I now add a code
div.hikashop_container {margin: 0px 10px 0px 10px; }
or similar to the frontend_default css file that does not change anything.

The line
#hikashop_category_information_menu_129 div.hikashop_container {
margin:5px 5px;
}
stays the same.

Hope it´s understandable now.