the current template override goes as far as only the "structural" template files and doesn't override the css files nicely and i have so far been forced to hack and do the following on each of my projects repeatedly so i want to suggest to fotis to try to incorporate it so that we can have css files as well customized
shut down the plugins/system/k2.php:#67 if clause
add a includeStyleSheet function to components/com_k2/helpers/utilities.php which includes the css files IF only they exist in the overriding template folder, and if not it simply uses the default ones
add a call to K2HelperUtilities::includeStyleSheet($params);in the various item and itemlist views available right before parent::display($tpl);

i have attached the modified utilities.php for conveniencehoping to see this included soonthanks!