I have a half bath that I want to install a new vanity. The width from wall to wall is 30". Bath vanities come in 24" and 30" widths. I don't think that I can install a 30" vanity. If I install a 24", what can I use to cover the 3" gap on the sides so that I don't have "stuff" falling down between the wall and vanity? Just puzzled - thanks!