Solved: Silverstripe Problem adding styles to WYSIWYG editor

I was adding styles to my typography CSS file, which is the correct way to add custom styles that can be added / removed by the user in the editor:

.typography .homesubheading {
    color:#8fd3d2;
    text-align: center;
}

However these styles were not showing up in the Silverstripe mceEditor style selection dropdown box.

The reason is that my theme folder was not the default one set in the theme folder "simple". I had a different name to my theme folder, and this meant that the typography styles weren't being shown.

To set your style folder, add this to your site's _config.php

SSViewer::set_theme("lbc");

Then the styles will show up next time you refresh the WYSIWYG editor.