Hi, my forum is 3.0.12 and I haven't updated yet to 3.1 because my template isn't available in 3.1.
That mod has been abandoned so it is anybody's guess as to whether it works or not with any template and also support for the phpBB 3.0 branch ceased at the start of this year.
If your style inherits from prosilver you should apply the changes the same way you would do for prosilver