Allow color values to be defined multiple times, see http://plugins.trac.wordpress.org/changeset/683731
Add "viewport" @ rule (see http://plugins.trac.wordpress.org/changeset/698918/jetpack/trunk/modules/custom-css/csstidy/data-wp.inc.php)
CSS properties are not case-sensitive. Normalize them to lowercase (see https://github.com/cfinke/CSSTidy/commit/504a0e2018c2c956208120811da155aab66b6da5)