Example of using prefix/suffix/separators/etc, e.g. placing subcategories into columns

It is better to set these in Component configuration to avoid setting it in every category.
In Component configuration,  in content lists TAB, find sub-categories configuration, and set these:

1. Prefix text of every record:
   

   <span style="display:inline-block; width:200px; float:left;white-space:nowrap">

2. Suffix text of every record:
   

   </span>

3. Record Separator: Space
   
   
4. Opening text for record list:
   

   <div class="fcclear"></div>

5. Closing text for record list: nothing
   
   

-- In your categories, make sure the above are empty, and that Record Separator is to "Use Global"
-- Test frontend and update CSS of prefix text to match your needs e.g. adding height too, or border, etc,
-- you may also want to use a CSS class instead of inline CSS