Hi Gareth,
I'm not sure how I can set the css override to appear or not appear based on a theme checkbox with all the style presets.
Let me rethink this approach. Maybe it might make sense to not override the color settings. It would be easy enough to take out and more work to try and include this as setting.
It's been our experience in K-12 that when the CT course format is installed that the site admin isn't concerned or isn't knowledgeable enough to know what and how to setup the CT course defaults so in 95% of the setups they just use whatever settings you put in it when you set the default options. Many times the Moodle admin is just the one teacher who wanted to use Moodle the most and they have no formal training or experience to properly setup and maintain all the things that a proper Moodle admin would do.
With that in mind we designed Fordson so that it could be installed with very little configuration beyond the defaults and get great results that made teachers decide to take another look at using Moodle in the school districts in my area. We have a formula of some pretty basic services that have districts in Michigan beginning to take another look at Moodle as a LMS. For a K-12 teacher, the use of a LMS is usually optional so we wrap some basic services and a great user experience via Fordson and Easy Enrollment with Moodle and it is gaining usage in our area.
I'm really debating what is the best approach as I can clearly see the site admin can change the default options for teachers in the plugin settings. Our issue is that often times they do not and then the course format looks poorly because of the default colors and this takes away from the overall user experience.
I included this small change so that our districts could begin using CT as an option for our learning platform and still get a seamless and unified look and feel throughout the site regardless of which course format you choose.
I guess it is open for discussion.