How to add offset value as serial number in ListView?

Currently, I want to add serial number or row number in ListView. I was trying by copying from include/ListView/ListViewGeneric.tpl to custom/modules/(mymodule)/tpl/LitsViewGeneric.tpl.
It works with that but my problem is css design has broken after including custom one.
Is there anyway to print the offset value as serial number by updating include/ListView/ListViewGeneric.tpl.
If I update this file then it does not show any affect. IS there any solution for this?
Plz let me know.

Thanks in advance