If you'd like to define a few super-simple custom panels pane styles, here's the bare bones code.

In a custom module:

<?php 
/**
 * Implements hook_ctools_plugin_directory().
 */
function grasmash_panels_ctools_plugin_directory($module, $plugin) {
  if ($module == 'panels' && $plugin == 'styles') {
    return 'plugins/' . $plugin;
  }
}
?>

In plugins/styles/gold.inc:

<?php

/**
 * @file
 * Defines "Gold Border" style.
 */

/**
 * Implements hook_panels_style_info().
 */
function grasmash_panels_gold_panels_styles() {
  return array(
    'title' => t('Gold Border'),
    'description' => t('Displays the pane with a gold border.'),
    'render pane' => 'grasmash_panels_gold_render_pane',
  );
}

/**
 * Render callback for "gold" panels pane style. Mimics default panel pane.
 */
function theme_grasmash_panels_gold_render_pane($vars) {
  return theme('panels_pane', array(
    'content' => $vars['content'],
    'pane' => $vars['pane'],
    'display' => $vars['display'],
  ));
}
?>

In your theme:

<?php
/**
 * Implements template_preprocess_panels_pane().
 */
function grasmashtheme_preprocess_panels_pane(&$vars) {
  if (!empty($vars['pane']->style['style'])) {
    $style = $vars['pane']->style['style'];
    $vars['classes_array'][] = 'panels-pane-style-' . drupal_clean_css_identifier($style);
  }
}
?>

    .panels-pane-style-gold {
      border: 4px solid gold;
    }