Hi Mary,
Thanks for your help, from what you have suggested I have been able to effect certain elements of the course-box's by altering certain attributes as below:
#page .covtiles.panel .panel-body a[href*="2"]
{opacity: 0.5 !important;}
#page .covtiles.panel .panel-body .cimbox[style*="infect"]
{opacity: 0.5 !important;}
This works as a workaround for now but I am still struggling to just select a single course-box with course id, i'm not sure if this is something that can be done in the adaptable theme when using covtiles, because I looked at the boost theme and I could see the [data-course-id] attribute you mentioned when using course-boxes on the frontpage. I also changed the adaptable theme list options to the moodle default and I could see a course id attribute like this [data-courseid="6"], but when I switched back to covtiles, there was no attributes for course id.
The workaround I have, works for me at the minute but if anyone does come across the way to do this by using the adaptable theme and covtiles then it would be useful to know.
Thanks,
Dan.