The Theme Editor menu allows you to edit the individual CSS and PHP files which make up your Theme. Normally once a theme is installed and configured on your site, there's no need to make any changes within here. Extreme care should be taken with this option to avoid making changes to files that will affect how your site is displayed. Incorrectly modifying any files within this section can cause your site to display incorrectly or at worst, not at all. Extra caution must be taken if you intend to make any changes here.
|It cannot be stressed enough how dangerous this option is if you know nothing about HTML, CSS or PHP. Modifying your theme files can drastically change how your site displays and depending on what gets changed, can even stop your site from displaying altogether.|