Removes the id attribute from style tags, enabling mod_pagespeed to combine those files

pagespeed-css-combination-fix.php

<?php
/*
Plugin Name: Pagespeed CSS Combination Fix
Plugin URI: https://gist.github.com/2ndkauboy/7154341
Description: Removes the id attribute from style tags, enabling mod_pagespeed to combine those files
Version: 0.1
Author: Bernhard Kau
Author URI: http://kau-boys.de
*/

function remove_id_form_pagespeed_optimization( $style_tag ){
	
	if ( !is_admin() ) {
		$style_tag = preg_replace( "/id='.*-css'\s?/", '', $style_tag );
	}
	
	return $style_tag;
}
add_filter( 'style_loader_tag', 'remove_id_form_pagespeed_optimization' );