headings and formating

You can change the CSS of hikashop via the interface in the Display tab of the config.
The layouts can be modified via the menu Display->Views.

Here is the documentation of the configuration page with screenshots of the interface where you can edit the CSS:
www.hikashop.com/en/support/documentatio...-config.html#display

Here is the same for the view edition:
www.hikashop.com/en/support/documentatio...op-view-listing.html