Removing Unnecessary CSS Files I am in the process of optimizing my Drupal site by removing unnecessary css files. 

Running an audit I have found that /misc/ui/jquery.ui.core.css, /misc/ui/jquery.ui.theme.css and /misc/ui/jquery.ui.slider.css are relatively large but are never called. 

I have tried removing them in my template.php file with the following but they still remain. How can I unset them?

unset($css[DRUPAL_ROOT.'/misc/ui/jquery.ui.slider.css']);
unset($css[DRUPAL_ROOT.'/misc/ui/jquery.ui.core.css']);
unset($css[DRUPAL_ROOT.'/misc/ui/jquery.ui.theme.css']);
You can use hook_ccs_alter 

function yourmodule_css_alter(&amp;$css) {

  unset($css['misc/ui/jquery.ui.core.css']);
}