Dear Gareth, Mary and Chris,
Thank you soooo much for your very kind and useful support.
I have been able to make it work exactly as I wanted.
I have used the preset from Chris, and modified the colours in the plugin from Gareth. It works perfectly, see the picture below.
Mary, I have tried the code, and it is absolutely useful. It could help on highlighting some very important topics in the course.
I just have a comment: Would it be possible to have the preset from Chris available by default in the theme, with a kind of "warning" like: In case you use the Collapsed Topics plugin? Or maybe, the preset available on the theme's description in Moodle.org with the same explanation?
And also, a same kind of warning on the Collapsed Topics plugin description page on Moodle.org, saying "in case you use the Fordson theme, use the preset available here" and a link to the file.
I think that would help future users.
Anyway, all is excellent. I really appreciate your support.
You helped me become a Happy Moodler ;o)