use drupal_add_css to add css

I use Drupal's css aggregation to combine all the css stylesheets into one css file. This can drastically reduce the number of http requests per page when lots of modules are being used, many of which provide their own css files - resulting in much better webserver performance and faster page loads for clients.

The 4 stylesheets added by the pagestyle module are not able to be included in the css aggregation, which results in 4 additional http requests per page - one for each stylesheet. As I understand it, Drupal is only capable of aggregating css files added with the drupal_add_css function. Why do you add the styles manually through drupal_set_html_head() rather than using drupal_add_css()?