Heloo ... nice to be here....   i have  a small problem, hope that you can help. I've seen that you don't provide a child theme so i build one myself and everything was going well until i changed Permalinks to Friendly urls. My Style.css stoped working ...if i change back my permalinks it start working, but a really want to use Friendly urls....   

i created zara_child folder and inside i have index.php with this code in

/*
  Theme Name: zara_child
  Theme URI: http://www.romert.ro
  Description: This is the Osclass CHILD zara theme
  Version: 1.0
  Author: AlinCG
  Author URI: http://www.romert.ro
  Parent Theme: zara
*/



and functions.php with:

   <?php
osc_enqueue_style('main', 'oc-content/themes/zara_child/css/style.css');
?>

 and then the css folder with style.css and admin folder

Do i need to do something else?   ... i would really apriciate if you could help me, i am new to Osclass ...i need style.css in child theme and friendly urls ....  Thank You!!!

@Alin
What I know child theme should work ok, as @Ghany was able to configure it correctly.
Please check what is URL to style.css what is problem there...
I would say you have assigned style relatively that does not work on nice URLs, you are missing your base url there. Check head.css for reference.