I would just do:
@overlay EFFECT DIM 60 opacity 1 in 0
OR:
@overlay EFFECT DIM 60 opacity 0.5 in 0
So it won’t be that dark. 
I would just do:
@overlay EFFECT DIM 60 opacity 1 in 0
OR:
@overlay EFFECT DIM 60 opacity 0.5 in 0
So it won’t be that dark. 