Panel layout body class

drupal_panel_layout_body_class.php

// Place this in mymodule.module

/**
 * Implements hook_panels_pre_render().
 */
function mymodule_panels_pre_render($panels_display, $renderer) {

  // Add a body class for all panel layouts present on a given page. This
  // functionality piggy-backs on Panels 'body_classes_to_add' functionality.
  // And let's us do clever things like null out the max-width of container
  // regions on certain layouts where we need region wrappers inside the panel
  // to reach the edge of a page, for theming purposes.
  $panel_body_css = &drupal_static('panel_body_css');
  $layout_class = drupal_html_class($panels_display->layout);
  if (!empty($panel_body_css['body_classes_to_add'])) {
    $panel_body_css['body_classes_to_add'] .= ' ' . $layout_class;
  } else {
    $panel_body_css['body_classes_to_add'] = $layout_class;
  }
}