Selective CSS Aggregation for fast D7 development performance
At this time, it appears this module is not needed for Drupal 7
this has been committed and fixed in D7 core.

refer to this:

IE: Stylesheets ignored after 31 link/style tags

==========
css aggregation of all stylesheets EXCEPT certain one. just add this to your theme's template file

drupal_add_css(drupal_get_path('theme', 'mytheme') . '/css/custom.css', array(
'group' =&gt; CSS_DEFAULT,
'preprocess' =&gt; FALSE,
'every_page' =&gt; TRUE
));