Overide Panels CSS

panels override css

Due to this great code, it should just work. But it doesn't.

function panels_get_layout($layout, $content) {
  $output = theme($layout['theme'], check_plain($layout['css_id']), $content);

  if ($output) {
    if (file_exists(path_to_theme() . '/' . $layout['css'])) {
      drupal_add_css(path_to_theme() . '/' . $layout['css']);
    }
    else {
      drupal_add_css(drupal_get_path('module', $layout['module']) . '/' . $layout['css']);
    }
  }
  return $output;
}

Ahh: the way the code is written, it must be in a directory called 'layouts':

A little drupal_set_message($layout['css']); and all is revealed:

layouts/threecol_33_34_33_stacked.css

Resolution

Put your copies of threecol_33_34_33_stacked.css and brethren in yourthemename/layouts/ just like they're in panels/layouts/