Program 4 sets of independent RGB LED's fading them from different colours

Hi,
I would like to program 4 sets of LED's with a range of colours, I would prefer to use HTML CSS coding to code the colours if that is at all possible, so I can easily work out the colours that I want to use.

I've set up my circuit already, so I'm ready to code. I've been able to get one of the sets to fade, but now i want to add 3 more to that. Thanks for your help, I really need it.

josh