how convert my custom css to 1.2?

how convert my custom css to 1.2?

With 1.1 I have a structure css and a custom css made with the theme roller. With 1.2 there seems to be only one css file and there is no theme roller for it currently available.

I've tried to get the 1.2 working with my custom theme but I can't seem to get it to work correctly. Any advice on what to do?