This component displays the names of the style (ClassName) and HTML element (id) under the mouse pointer and allows you to write CSS and JavaScript directly on the page without saving to an external file then importing that file through a Content Edtior web part. This is useful for developing client-side customizations.

 

NOTE: This web part is not real exciting under anonymous access, since "Apply Changes" won't save what you do. To see it work, you need to have some rights to the site. I'm still trying to figure out how to grant limited rights to anonymous users within Office 365, but so far it looks locked down pretty tight. You can allow anonymous users rights within normal SharePoint sites, but Office 365 provides a subset of normal SharePoint features.