Hi,
It's normal that you get custom 1 or custom 2 when you edit the file as HikaShop creates an override of the file so that you don't loose your changes when you update.
If you don't see any change on your frontend after that, it's either that :
- you have some caching on your website (and thus it's still using the old file) . So you should clear your joomla cache
- you have some optimization extension or settings of your Joomla template which compress/cache the CSS of your website. Clearing, or disable that optimization/caching on your website will allow you to see your changes.