Renovating the bathroom, we would like to use a 300mm x 300mm dark charcoal floor tile. Does this mean we should use a 300mm x 100mm white subway tile on the wall or can we use a 400mm x 100mm white wall tile? Our current bathroom has a 400x100 white wall tile and the previous owners used a 200mm x 200mm floor tile. It is a fairly small and simple bathroom. Any advice would be greatly appreciated, thanks.