Alter CSS allows you edit the CSS of a Drupal theme within Drupal. Upon installation, Alter CSS will add a fieldset to all theme administration pages that allows you to edit the text of style.css in your Drupal themes. Backup files are created when you first browse to a theme administration page for safe restoration and removed after uninstalling. You can create many different CSS files that you can switch through at any time through the same page. This is good for creating different "themes" within a Drupal theme.