4095 Selectors Limit on IE. How to split the Drupal 7 CSS compressed files?
Lets say your my_theme.info have

stylesheets[all][] = css/my_theme_1.css
stylesheets[all][] = css/my_theme_2.css
stylesheets[all][] = css/my_theme_3.css
stylesheets[all][] = css/my_theme_4.css


And you don't want to aggregate these files in a single one (exceed IE limit 4095 selectors)(also I assume that is already minified by Brunch)

Remove the above lines from your .info or comment out.

Then add an html preprocess function (on the main template.php or if you have an html.preprocess.inc file)

function my_theme_preprocess_html(&amp;$variables) {
  drupal_add_css(drupal_get_path('theme', 'my_theme') . '/css/my_theme_1.css', array('preprocess' =&gt; FALSE));
}


The drupal_add_css will add the css but 'preprocess' =&gt; FALSE will prevent Drupal to aggregate them.

(It's a bit hacky but it works)