Add new stlyes to Rich Text Editor ribbon in SP2013 Online

Question

I'm working with the preview version of Office 365 at the moment and would like users to be able to select the Callout 2 option which was available in SP2010 and we've been using for particular elements on pages. I'd like to add this to the available Text Styles in SP2013:

Answer 1

The styles you are refering in SharePoint are all generated via classes such as "ms-rte". So the issues of replacing or adding others is reduced to introducing new classes (see more here http://www.rightpoint.com/community/blogs/viewpoint/archive/2010/08/16/overriding-sharepoint-2010-rte-css-classes.aspx), do not forget the "ms-name" attribute, as in "Heading 2":

.ms-rteElement-H2 
{ 
    -ms-name:"Heading 2"; 
    font-size: 16px; 
    font-weight: normal; 
    text-align:left; 
    color:#cccccc; 
} 

Please be aware that there are 2 categories, "Styles" and "Markup Styles" (also explained detailed http://mosshowto.blogspot.ch/2009/12/sharepoint-2010-wiki-styles.html). In order to achieve this you have many ways, some of which:

1. In SharePoint 2013 / Office 365 - use the Composite Looks to update .spFont file (new theme or existing)
2. In SharePoint 2010 (on-premises or online) - via the master page if you want same experience across all site where used, or simply via a CEWP (Content Editor), or via the Page Layout (for Publishing Sites).