How to create custom style for quicktabs on D7 ?

Hi

after research, i made a module which contain this code, adapt from
the original module one :

function pf_qt_style_quicktabs_tabstyles() {
 $custom_tabstyles_directory = '_custom'.drupal_get_path('module', 'pf_qt_style') . '/quicktabs';
  $files = file_scan_directory($custom_tabstyles_directory, '/\.css$/');
  $custom_tabstyles = array();
  foreach ($files as $file) {
    // Skip RTL files.
    if (!strpos($file->name, '-rtl')) {
      $custom_tabstyles[$file->uri] = drupal_ucfirst($file->name);
    }
  }
  return $custom_tabstyles;

i put my module in sites/all/modules/_custom
then i activate it...the style is available in the select list on QT settings...ok
but i've a trouble with my css path...
actually it would be : sites/all/modules/_custom/pf_qt_style/quicktabs/cyrano/cyrano.css
but i don't know how to check this on the website to verify it...
all seem ok ,i guess

thanks for help