Different Styles depending on sidebars' existance (Holy Grail)

I have a basic theme I use to make all the Drupal themes for clients based on theHoly Grail (http://alistapart.com/articles/holygrail) layout.

Yesterday, I noticed that my theme no longer works on Drupal 5 installations. I read the Converting 4.7.x themes to 5.x (http://drupal.org/node/64292) page to find that drupal_add_css() (http://api.drupal.org/api/HEAD/function/drupal_add_css) is now the new way to add CSS.

Now, the idea is that I load one of four style sheets containing the structural styles for the Holy Grail:

Both sidebars, left sidebar, right sidebar and no sidebars.

I used to do this in page.tpl.php, but drupal_add_css() does not work there. I then tried moving the logic to template.php, but in there, in function _phptemplate_variables($hook, $vars) {, it is only possible to check if sidebars are existant after it is no longer possible to use drupal_add_css().

I asked in #drupal-support, last night and this morning but no one knew or were available to help with this.

The solution I found then, after reading the Converting 4.7.x themes to 5.x (http://drupal.org/node/64292) page again, regarding the availability of the $css variable on the theme level, was to add this to the page.tpl.php file:

  if (!$sidebar_left && !$sidebar_right) {
    $css['theme'][path_to_theme() . '/hg_one_center.css'] =
      array('path' => path_to_theme() . '/hg_one_center.css', 'media' => 'all'); }
  if ( $sidebar_left && !$sidebar_right) {
    $css['theme'][path_to_theme() . '/hg_two_left.css'] =
      array('path' => path_to_theme() . '/hg_two_left.css', 'media' => 'all'); }
  if (!$sidebar_left &&  $sidebar_right) {
    $css['theme'][path_to_theme() . '/hg_two_right.css'] =
      array('path' => path_to_theme() . '/hg_two_right.css', 'media' => 'all'); }
  if ( $sidebar_left &&  $sidebar_right) {
    $css['theme'][path_to_theme() . '/hg_three.css'] =
      array('path' => path_to_theme() . '/hg_three.css', 'media' => 'all'); }
  print drupal_get_css($css);
 

I added it in place of print $styles .

While this does work, I'd apreciate any advice on a more elegant solution.