Hook_css_alter custom

gistfile1.txt

function theme_css_alter(&$css) {
  // Css Not allowed for theming
  $not_allowed_css = array(
    'modules/system/system.base.css',
    'modules/system/system.menus.css',
    'modules/system/system.messages.css',
    'modules/system/system.theme.css',
    'sites/all/modules/contrib/ctools/css/ctools.css',    
  );
  foreach ($css as $css_filename => $css_settings) {
    if (in_array($css_filename, $not_allowed_css)) {
      unset($css[$css_filename]);
    }
  }
}