I'm not sure position overrides works with this template, as I haven't used it before.
But if you check into what those are, I'm pretty sure you can make it so. If not, you can change the template itself, after duplicating it and creating another version of it (so the "original" is kept as it is.
I added some resources that might help you in the right direction.
Thanks Kenneth! You provided me with a good direction and I have studied very important topics these days: “Overriding a Position” and Using Position Variations. It will definitely benefit me in the future. Sorry, but these topics are not useful for my specific question: 1. “Overriding a Position” does not work in the List, i.e. where we apply chart tamplate 2. I was surprised to find that using Chart Tamplate Using Position Variations does not work !!! Moreover, I tried to apply the built-in “Variation” to : seb_css3 or seb_css3b: without result, this does not affect the output!
Copy the folder on you server/local for the chart template. Go into the file templateDetails.xml in this new folder and change <name>NEW NAME HERE</name>
Then in Joomla administrator go to Extension -> Manage -> Discover. If no items is in this list, push "Discover" button before you select and push "Install" button.
Go to Seblod -> Templates -> New. Then add a name for it, folder, and select the template you just copied and renamed in step 1. Type pick list. Save.
Go to the seach & list type and change to this newly addded template, check if it works. If it does, then you can go ahead and change this copy of the template to your liking, without changing the original template. (The file you then need to change is index.php in the cloned template folder)